diff --git a/src/FGFDMExec.cpp b/src/FGFDMExec.cpp
index 66c96504ec..e207402695 100644
--- a/src/FGFDMExec.cpp
+++ b/src/FGFDMExec.cpp
@@ -74,7 +74,7 @@ CLASS IMPLEMENTATION
 // Constructor
 
 FGFDMExec::FGFDMExec(FGPropertyManager* root, unsigned int* fdmctr)
-  : Root(root), RandomEngine(new default_random_engine), FDMctr(fdmctr)
+  : FGJSBBase(cData), Root(root), RandomEngine(new default_random_engine), FDMctr(fdmctr)
 {
   Frame           = 0;
   IC              = nullptr;
@@ -106,9 +106,9 @@ FGFDMExec::FGFDMExec(FGPropertyManager* root, unsigned int* fdmctr)
 
   try {
     char* num = getenv("JSBSIM_DEBUG");
-    if (num) debug_lvl = atoi(num); // set debug level
+    if (num) gdata().debug_lvl = atoi(num); // set debug level
   } catch (...) {                   // if error set to 1
-    debug_lvl = 1;
+    gdata().debug_lvl = 1;
   }
 
   if (Root == 0) {                 // Then this is the root FDM
@@ -571,13 +571,13 @@ bool FGFDMExec::RunIC(void)
   Propagate->InitializeDerivatives();
   ResumeIntegration(); // Restores the integration rate to what it was.
 
-  if (debug_lvl > 0) {
+  if (gdata().debug_lvl > 0) {
     MassBalance->GetMassPropertiesReport(0);
 
-    cout << endl << fgblue << highint
+    cout << endl << gdata().fgblue << gdata().highint
          << "End of vehicle configuration loading." << endl
          << "-------------------------------------------------------------------------------"
-         << reset << std::setprecision(6) << endl;
+         << gdata().reset << std::setprecision(6) << endl;
   }
 
   for (unsigned int n=0; n < propulsion->GetNumEngines(); ++n) {
@@ -703,16 +703,16 @@ bool FGFDMExec::LoadModel(const string& model, bool addModelToPath)
     Allocate();
   }
 
-  int saved_debug_lvl = debug_lvl;
+  int saved_debug_lvl = gdata().debug_lvl;
   FGXMLFileRead XMLFileRead;
   Element *document = XMLFileRead.LoadXMLDocument(aircraftCfgFileName); // "document" is a class member
 
   if (document) {
-    if (IsChild) debug_lvl = 0;
+    if (IsChild) gdata().debug_lvl = 0;
 
     ReadPrologue(document);
 
-    if (IsChild) debug_lvl = saved_debug_lvl;
+    if (IsChild) gdata().debug_lvl = saved_debug_lvl;
 
     // Process the fileheader element in the aircraft config file. This element is OPTIONAL.
     Element* element = document->FindElement("fileheader");
@@ -724,7 +724,7 @@ bool FGFDMExec::LoadModel(const string& model, bool addModelToPath)
       }
     }
 
-    if (IsChild) debug_lvl = 0;
+    if (IsChild) gdata().debug_lvl = 0;
 
     // Process the planet element. This element is OPTIONAL.
     element = document->FindElement("planet");
@@ -892,12 +892,12 @@ bool FGFDMExec::LoadModel(const string& model, bool addModelToPath)
 
     modelLoaded = true;
 
-    if (IsChild) debug_lvl = saved_debug_lvl;
+    if (IsChild) gdata().debug_lvl = saved_debug_lvl;
 
   } else {
-    cerr << fgred
+    cerr << gdata().fgred
          << "  JSBSim failed to open the configuration file: " << aircraftCfgFileName
-         << fgdef << endl;
+         << gdata().fgdef << endl;
   }
 
   for (unsigned int i=0; i< Models.size(); i++) LoadInputs(i);
@@ -964,8 +964,8 @@ string FGFDMExec::QueryPropertyCatalog(const string& in)
 void FGFDMExec::PrintPropertyCatalog(void)
 {
   cout << endl;
-  cout << "  " << fgblue << highint << underon << "Property Catalog for "
-       << modelName << reset << endl << endl;
+  cout << "  " << gdata().fgblue << gdata().highint << gdata().underon << "Property Catalog for "
+       << modelName << gdata().reset << endl << endl;
   for (unsigned i=0; i<PropertyCatalog.size(); i++) {
     cout << "    " << PropertyCatalog[i] << endl;
   }
@@ -988,10 +988,10 @@ bool FGFDMExec::ReadFileHeader(Element* el)
 {
   bool result = true; // true for success
 
-  if (debug_lvl == 0) return result;
+  if (gdata().debug_lvl == 0) return result;
 
   if (IsChild) {
-    cout << endl <<highint << fgblue << "Reading child model: " << IdFDM << reset << endl << endl;
+    cout << endl << gdata().highint << gdata().fgblue << "Reading child model: " << IdFDM << gdata().reset << endl << endl;
   }
 
   if (el->FindElement("description"))
@@ -1017,50 +1017,50 @@ bool FGFDMExec::ReadPrologue(Element* el) // el for ReadPrologue is the document
   string AircraftName = el->GetAttributeValue("name");
   ((FGAircraft*)Models[eAircraft])->SetAircraftName(AircraftName);
 
-  if (debug_lvl & 1) cout << underon << "Reading Aircraft Configuration File"
-            << underoff << ": " << highint << AircraftName << normint << endl;
+  if (gdata().debug_lvl & 1) cout << gdata().underon << "Reading Aircraft Configuration File"
+            << gdata().underoff << ": " << gdata().highint << AircraftName << gdata().normint << endl;
 
   CFGVersion = el->GetAttributeValue("version");
   Release    = el->GetAttributeValue("release");
 
-  if (debug_lvl & 1)
-    cout << "                            Version: " << highint << CFGVersion
-                                                    << normint << endl;
+  if (gdata().debug_lvl & 1)
+    cout << "                            Version: " << gdata().highint << CFGVersion
+                                                    << gdata().normint << endl;
   if (CFGVersion != needed_cfg_version) {
-    cerr << endl << fgred << "YOU HAVE AN INCOMPATIBLE CFG FILE FOR THIS AIRCRAFT."
+    cerr << endl << gdata().fgred << "YOU HAVE AN INCOMPATIBLE CFG FILE FOR THIS AIRCRAFT."
             " RESULTS WILL BE UNPREDICTABLE !!" << endl;
     cerr << "Current version needed is: " << needed_cfg_version << endl;
-    cerr << "         You have version: " << CFGVersion << endl << fgdef << endl;
+    cerr << "         You have version: " << CFGVersion << endl << gdata().fgdef << endl;
     return false;
   }
 
-  if (Release == "ALPHA" && (debug_lvl & 1)) {
+  if (Release == "ALPHA" && (gdata().debug_lvl & 1)) {
     cout << endl << endl
-         << highint << "This aircraft model is an " << fgred << Release
-         << reset << highint << " release!!!" << endl << endl << reset
+         << gdata().highint << "This aircraft model is an " << gdata().fgred << Release
+         << gdata().reset << gdata().highint << " release!!!" << endl << endl << gdata().reset
          << "This aircraft model may not even properly load, and probably"
          << " will not fly as expected." << endl << endl
-         << fgred << highint << "Use this model for development purposes ONLY!!!"
-         << normint << reset << endl << endl;
-  } else if (Release == "BETA" && (debug_lvl & 1)) {
+         << gdata().fgred << gdata().highint << "Use this model for development purposes ONLY!!!"
+         << gdata().normint << gdata().reset << endl << endl;
+  } else if (Release == "BETA" && (gdata().debug_lvl & 1)) {
     cout << endl << endl
-         << highint << "This aircraft model is a " << fgred << Release
-         << reset << highint << " release!!!" << endl << endl << reset
+         << gdata().highint << "This aircraft model is a " << gdata().fgred << Release
+         << gdata().reset << gdata().highint << " release!!!" << endl << endl << gdata().reset
          << "This aircraft model probably will not fly as expected." << endl << endl
-         << fgblue << highint << "Use this model for development purposes ONLY!!!"
-         << normint << reset << endl << endl;
-  } else if (Release == "PRODUCTION" && (debug_lvl & 1)) {
+         << gdata().fgblue << gdata().highint << "Use this model for development purposes ONLY!!!"
+         << gdata().normint << gdata().reset << endl << endl;
+  } else if (Release == "PRODUCTION" && (gdata().debug_lvl & 1)) {
     cout << endl << endl
-         << highint << "This aircraft model is a " << fgblue << Release
-         << reset << highint << " release." << endl << endl << reset;
-  } else if (debug_lvl & 1) {
+         << gdata().highint << "This aircraft model is a " << gdata().fgblue << Release
+         << gdata().reset << gdata().highint << " release." << endl << endl << gdata().reset;
+  } else if (gdata().debug_lvl & 1) {
     cout << endl << endl
-         << highint << "This aircraft model is an " << fgred << Release
-         << reset << highint << " release!!!" << endl << endl << reset
+         << gdata().highint << "This aircraft model is an " << gdata().fgred << Release
+         << gdata().reset << gdata().highint << " release!!!" << endl << endl << gdata().reset
          << "This aircraft model may not even properly load, and probably"
          << " will not fly as expected." << endl << endl
-         << fgred << highint << "Use this model for development purposes ONLY!!!"
-         << normint << reset << endl << endl;
+         << gdata().fgred << gdata().highint << "Use this model for development purposes ONLY!!!"
+         << gdata().normint << gdata().reset << endl << endl;
   }
 
   return result;
@@ -1099,16 +1099,16 @@ bool FGFDMExec::ReadChild(Element* el)
     child->Loc = location->FindElementTripletConvertTo("IN");
   } else {
     const string s("  No location was found for this child object!");
-    cerr << el->ReadFrom() << endl << highint << fgred
-         << s << reset << endl;
+    cerr << el->ReadFrom() << endl << gdata().highint << gdata().fgred
+         << s << gdata().reset << endl;
     throw BaseException(s);
   }
 
   Element* orientation = el->FindElement("orient");
   if (orientation) {
     child->Orient = orientation->FindElementTripletConvertTo("RAD");
-  } else if (debug_lvl > 0) {
-    cerr << endl << highint << "  No orientation was found for this child object! Assuming 0,0,0." << reset << endl;
+  } else if (gdata().debug_lvl > 0) {
+    cerr << endl << gdata().highint << "  No orientation was found for this child object! Assuming 0,0,0." << gdata().reset << endl;
   }
 
   ChildFDMList.push_back(child);
@@ -1168,7 +1168,7 @@ void FGFDMExec::DoTrim(int mode)
   FGTrim trim(this, (JSBSim::TrimMode)mode);
   bool success = trim.DoTrim();
 
-  if (debug_lvl > 0)
+  if (gdata().debug_lvl > 0)
     trim.Report();
 
   if (!success)
@@ -1182,7 +1182,7 @@ void FGFDMExec::DoTrim(int mode)
 void FGFDMExec::SRand(int sr)
 {
   RandomSeed = sr;
-  gaussian_random_number_phase = 0;
+  gdata().gaussian_random_number_phase = 0;
   RandomEngine->seed(sr);
   srand(RandomSeed);
 }
@@ -1208,9 +1208,9 @@ void FGFDMExec::SRand(int sr)
 
 void FGFDMExec::Debug(int from)
 {
-  if (debug_lvl <= 0) return;
+  if (gdata().debug_lvl <= 0) return;
 
-  if (debug_lvl & 1 && IdFDM == 0) { // Standard console startup message output
+  if (gdata().debug_lvl & 1 && IdFDM == 0) { // Standard console startup message output
     if (from == 0) { // Constructor
       cout << "\n\n     "
            << "JSBSim Flight Dynamics Model v" << JSBSim_version << endl;
@@ -1221,21 +1221,21 @@ void FGFDMExec::Debug(int from)
       cout << "\n\nJSBSim startup complete\n\n";
     }
   }
-  if (debug_lvl & 2 ) { // Instantiation/Destruction notification
+  if (gdata().debug_lvl & 2 ) { // Instantiation/Destruction notification
     if (from == 0) cout << "Instantiated: FGFDMExec" << endl;
     if (from == 1) cout << "Destroyed:    FGFDMExec" << endl;
   }
-  if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
+  if (gdata().debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
     if (from == 2) {
       cout << "================== Frame: " << Frame << "  Time: "
            << sim_time << " dt: " << dT << endl;
     }
   }
-  if (debug_lvl & 8 ) { // Runtime state variables
+  if (gdata().debug_lvl & 8 ) { // Runtime state variables
   }
-  if (debug_lvl & 16) { // Sanity checking
+  if (gdata().debug_lvl & 16) { // Sanity checking
   }
-  if (debug_lvl & 64) {
+  if (gdata().debug_lvl & 64) {
     if (from == 0) { // Constructor
     }
   }
diff --git a/src/FGFDMExec.h b/src/FGFDMExec.h
index a02dcd4d2e..f8cda33be3 100644
--- a/src/FGFDMExec.h
+++ b/src/FGFDMExec.h
@@ -500,7 +500,7 @@ class JSBSIM_API FGFDMExec : public FGJSBBase
       @param mode Sets the reset mode.*/
   void ResetToInitialConditions(int mode);
   /// Sets the debug level.
-  void SetDebugLevel(int level) {debug_lvl = level;}
+  void SetDebugLevel(int level) {gdata().debug_lvl = level;}
 
   struct PropertyCatalogStructure {
     /// Name of the property.
@@ -591,7 +591,7 @@ class JSBSIM_API FGFDMExec : public FGJSBBase
   unsigned int GetFrame(void) const {return Frame;}
 
   /** Retrieves the current debug level setting. */
-  int GetDebugLevel(void) const {return debug_lvl;};
+  int GetDebugLevel(void) const {return gdata().debug_lvl;};
 
   /** Initializes the simulation with initial conditions
       @param FGIC The initial conditions that will be passed to the simulation. */
@@ -620,6 +620,7 @@ class JSBSIM_API FGFDMExec : public FGJSBBase
   { return RandomEngine; }
 
 private:
+  CommonData cData;
   unsigned int Frame;
   unsigned int IdFDM;
   int disperse;
diff --git a/src/FGJSBBase.cpp b/src/FGJSBBase.cpp
index 09d45689b7..49a98f73c6 100644
--- a/src/FGJSBBase.cpp
+++ b/src/FGJSBBase.cpp
@@ -47,49 +47,14 @@ namespace JSBSim {
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
-
-#ifndef _MSC_VER
-    char FGJSBBase::highint[5]  = {27, '[', '1', 'm', '\0'      };
-    char FGJSBBase::halfint[5]  = {27, '[', '2', 'm', '\0'      };
-    char FGJSBBase::normint[6]  = {27, '[', '2', '2', 'm', '\0' };
-    char FGJSBBase::reset[5]    = {27, '[', '0', 'm', '\0'      };
-    char FGJSBBase::underon[5]  = {27, '[', '4', 'm', '\0'      };
-    char FGJSBBase::underoff[6] = {27, '[', '2', '4', 'm', '\0' };
-    char FGJSBBase::fgblue[6]   = {27, '[', '3', '4', 'm', '\0' };
-    char FGJSBBase::fgcyan[6]   = {27, '[', '3', '6', 'm', '\0' };
-    char FGJSBBase::fgred[6]    = {27, '[', '3', '1', 'm', '\0' };
-    char FGJSBBase::fggreen[6]  = {27, '[', '3', '2', 'm', '\0' };
-    char FGJSBBase::fgdef[6]    = {27, '[', '3', '9', 'm', '\0' };
-#else
-    char FGJSBBase::highint[5]  = {'\0' };
-    char FGJSBBase::halfint[5]  = {'\0' };
-    char FGJSBBase::normint[6]  = {'\0' };
-    char FGJSBBase::reset[5]    = {'\0' };
-    char FGJSBBase::underon[5]  = {'\0' };
-    char FGJSBBase::underoff[6] = {'\0' };
-    char FGJSBBase::fgblue[6]   = {'\0' };
-    char FGJSBBase::fgcyan[6]   = {'\0' };
-    char FGJSBBase::fgred[6]    = {'\0' };
-    char FGJSBBase::fggreen[6]  = {'\0' };
-    char FGJSBBase::fgdef[6]    = {'\0' };
-#endif
-
 const string FGJSBBase::needed_cfg_version = "2.0";
 const string FGJSBBase::JSBSim_version = JSBSIM_VERSION " " __DATE__ " " __TIME__ ;
 
-queue <FGJSBBase::Message> FGJSBBase::Messages;
-FGJSBBase::Message FGJSBBase::localMsg;
-unsigned int FGJSBBase::messageId = 0;
-
-int FGJSBBase::gaussian_random_number_phase = 0;
-
-short FGJSBBase::debug_lvl  = 1;
-
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 void FGJSBBase::PutMessage(const Message& msg)
 {
-  Messages.push(msg);
+  _gdata.Messages.push(msg);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -98,10 +63,10 @@ void FGJSBBase::PutMessage(const string& text)
 {
   Message msg;
   msg.text = text;
-  msg.messageId = messageId++;
+  msg.messageId = _gdata.messageId++;
   msg.subsystem = "FDM";
   msg.type = Message::eText;
-  Messages.push(msg);
+  _gdata.Messages.push(msg);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -110,11 +75,11 @@ void FGJSBBase::PutMessage(const string& text, bool bVal)
 {
   Message msg;
   msg.text = text;
-  msg.messageId = messageId++;
+  msg.messageId = _gdata.messageId++;
   msg.subsystem = "FDM";
   msg.type = Message::eBool;
   msg.bVal = bVal;
-  Messages.push(msg);
+  _gdata.Messages.push(msg);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -123,11 +88,11 @@ void FGJSBBase::PutMessage(const string& text, int iVal)
 {
   Message msg;
   msg.text = text;
-  msg.messageId = messageId++;
+  msg.messageId = _gdata.messageId++;
   msg.subsystem = "FDM";
   msg.type = Message::eInteger;
   msg.iVal = iVal;
-  Messages.push(msg);
+  _gdata.Messages.push(msg);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -136,40 +101,40 @@ void FGJSBBase::PutMessage(const string& text, double dVal)
 {
   Message msg;
   msg.text = text;
-  msg.messageId = messageId++;
+  msg.messageId = _gdata.messageId++;
   msg.subsystem = "FDM";
   msg.type = Message::eDouble;
   msg.dVal = dVal;
-  Messages.push(msg);
+  _gdata.Messages.push(msg);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 void FGJSBBase::ProcessMessage(void)
 {
-  if (Messages.empty()) return;
-  localMsg = Messages.front();
+  if (_gdata.Messages.empty()) return;
+  _gdata.localMsg = _gdata.Messages.front();
 
   while (SomeMessages()) {
-      switch (localMsg.type) {
-      case JSBSim::FGJSBBase::Message::eText:
-        cout << localMsg.messageId << ": " << localMsg.text << endl;
+      switch (_gdata.localMsg.type) {
+      case JSBSim::Message::eText:
+        cout << _gdata.localMsg.messageId << ": " << _gdata.localMsg.text << endl;
         break;
-      case JSBSim::FGJSBBase::Message::eBool:
-        cout << localMsg.messageId << ": " << localMsg.text << " " << localMsg.bVal << endl;
+      case JSBSim::Message::eBool:
+        cout << _gdata.localMsg.messageId << ": " << _gdata.localMsg.text << " " << _gdata.localMsg.bVal << endl;
         break;
-      case JSBSim::FGJSBBase::Message::eInteger:
-        cout << localMsg.messageId << ": " << localMsg.text << " " << localMsg.iVal << endl;
+      case JSBSim::Message::eInteger:
+        cout << _gdata.localMsg.messageId << ": " << _gdata.localMsg.text << " " << _gdata.localMsg.iVal << endl;
         break;
-      case JSBSim::FGJSBBase::Message::eDouble:
-        cout << localMsg.messageId << ": " << localMsg.text << " " << localMsg.dVal << endl;
+      case JSBSim::Message::eDouble:
+        cout << _gdata.localMsg.messageId << ": " << _gdata.localMsg.text << " " << _gdata.localMsg.dVal << endl;
         break;
       default:
         cerr << "Unrecognized message type." << endl;
         break;
       }
-      Messages.pop();
-      if (SomeMessages()) localMsg = Messages.front();
+     _gdata.Messages.pop();
+      if (SomeMessages()) _gdata.localMsg = _gdata.Messages.front();
       else break;
   }
 
@@ -177,30 +142,30 @@ void FGJSBBase::ProcessMessage(void)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGJSBBase::Message* FGJSBBase::ProcessNextMessage(void)
+Message* FGJSBBase::ProcessNextMessage(void)
 {
-  if (Messages.empty()) return NULL;
-  localMsg = Messages.front();
+  if (_gdata.Messages.empty()) return NULL;
+  _gdata.localMsg = _gdata.Messages.front();
 
-  Messages.pop();
-  return &localMsg;
+  _gdata.Messages.pop();
+  return &_gdata.localMsg;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 void FGJSBBase::disableHighLighting(void)
 {
-  highint[0]='\0';
-  halfint[0]='\0';
-  normint[0]='\0';
-  reset[0]='\0';
-  underon[0]='\0';
-  underoff[0]='\0';
-  fgblue[0]='\0';
-  fgcyan[0]='\0';
-  fgred[0]='\0';
-  fggreen[0]='\0';
-  fgdef[0]='\0';
+  _gdata.highint[0]='\0';
+  _gdata.halfint[0]='\0';
+  _gdata.normint[0]='\0';
+  _gdata.reset[0]='\0';
+  _gdata.underon[0]='\0';
+  _gdata.underoff[0]='\0';
+  _gdata.fgblue[0]='\0';
+  _gdata.fgcyan[0]='\0';
+  _gdata.fgred[0]='\0';
+  _gdata.fggreen[0]='\0';
+  _gdata.fgdef[0]='\0';
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -216,26 +181,25 @@ string FGJSBBase::CreateIndexedPropertyName(const string& Property, int index)
 
 double FGJSBBase::GaussianRandomNumber(void)
 {
-  static double V1, V2, S;
   double X;
 
-  if (gaussian_random_number_phase == 0) {
-    V1 = V2 = S = X = 0.0;
+  if (_gdata.gaussian_random_number_phase == 0) {
+    _gdata.V1 = _gdata.V2 = _gdata.S = X = 0.0;
 
     do {
       double U1 = (double)rand() / RAND_MAX;
       double U2 = (double)rand() / RAND_MAX;
 
-      V1 = 2 * U1 - 1;
-      V2 = 2 * U2 - 1;
-      S = V1 * V1 + V2 * V2;
-    } while(S >= 1 || S == 0);
+      _gdata.V1 = 2 * U1 - 1;
+      _gdata.V2 = 2 * U2 - 1;
+      _gdata.S = _gdata.V1 * _gdata.V1 + _gdata.V2 * _gdata.V2;
+    } while(_gdata.S >= 1 || _gdata.S == 0);
 
-    X = V1 * sqrt(-2 * log(S) / S);
+    X = _gdata.V1 * sqrt(-2 * log(_gdata.S) / _gdata.S);
   } else
-    X = V2 * sqrt(-2 * log(S) / S);
+    X = _gdata.V2 * sqrt(-2 * log(_gdata.S) / _gdata.S);
 
-  gaussian_random_number_phase = 1 - gaussian_random_number_phase;
+  _gdata.gaussian_random_number_phase = 1 - _gdata.gaussian_random_number_phase;
 
   return X;
 }
diff --git a/src/FGJSBBase.h b/src/FGJSBBase.h
index 75207ed112..ffb7c780a3 100644
--- a/src/FGJSBBase.h
+++ b/src/FGJSBBase.h
@@ -76,25 +76,83 @@ CLASS DOCUMENTATION
 CLASS DECLARATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
+/// JSBSim Message structure
+struct Message {
+  unsigned int fdmId;
+  unsigned int messageId;
+  std::string text;
+  std::string subsystem;
+  enum mType {eText, eInteger, eDouble, eBool} type;
+  bool bVal;
+  int  iVal;
+  double dVal;
+};
+
+// Common data for FGJSBBase, one instance on global scope,
+// A replacement for static variable(not support for multi-thread) in FGJSBBase.
+struct CommonData {
+  Message localMsg;
+  std::queue <Message> Messages;
+  unsigned int messageId = 0;
+
+  short debug_lvl = 1;
+  
+  int gaussian_random_number_phase = 0;
+  double V1 = 0.0;
+  double V2 = 0.0;
+  double S = 0.0;
+
+  ///@name JSBSim console output highlighting terms.
+  //@{
+#ifndef _MSC_VER
+  /// highlights text
+  char highint[5]  = {27, '[', '1', 'm', '\0'      };
+  /// low intensity text
+  char halfint[5]  = {27, '[', '2', 'm', '\0'      };
+  /// normal intensity text
+  char normint[6]  = {27, '[', '2', '2', 'm', '\0' };
+  /// resets text properties
+  char reset[5]    = {27, '[', '0', 'm', '\0'      };
+  /// underlines text
+  char underon[5]  = {27, '[', '4', 'm', '\0'      };
+  /// underline off
+  char underoff[6] = {27, '[', '2', '4', 'm', '\0' };
+  /// blue text
+  char fgblue[6]   = {27, '[', '3', '4', 'm', '\0' };
+  /// cyan text
+  char fgcyan[6]   = {27, '[', '3', '6', 'm', '\0' };
+  /// red text
+  char fgred[6]    = {27, '[', '3', '1', 'm', '\0' };
+  /// green text
+  char fggreen[6]  = {27, '[', '3', '2', 'm', '\0' };
+  /// default text
+  char fgdef[6]    = {27, '[', '3', '9', 'm', '\0' };
+#else
+  char highint[5]  = {'\0' };
+  char halfint[5]  = {'\0' };
+  char normint[6]  = {'\0' };
+  char reset[5]    = {'\0' };
+  char underon[5]  = {'\0' };
+  char underoff[6] = {'\0' };
+  char fgblue[6]   = {'\0' };
+  char fgcyan[6]   = {'\0' };
+  char fgred[6]    = {'\0' };
+  char fggreen[6]  = {'\0' };
+  char fgdef[6]    = {'\0' };
+#endif
+  //@}
+};
+
 class JSBSIM_API FGJSBBase {
 public:
   /// Constructor for FGJSBBase.
-  FGJSBBase() {};
+  FGJSBBase(CommonData& gdata) : _gdata(gdata) {};
 
   /// Destructor for FGJSBBase.
   virtual ~FGJSBBase() {};
 
-  /// JSBSim Message structure
-  struct Message {
-    unsigned int fdmId;
-    unsigned int messageId;
-    std::string text;
-    std::string subsystem;
-    enum mType {eText, eInteger, eDouble, eBool} type;
-    bool bVal;
-    int  iVal;
-    double dVal;
-  };
+  CommonData& gdata() { return _gdata; }
+  const CommonData& gdata() const { return _gdata; }
 
   /// First order, (low pass / lag) filter
   class Filter {
@@ -118,32 +176,6 @@ class JSBSIM_API FGJSBBase {
     }
   };
 
-  ///@name JSBSim console output highlighting terms.
-  //@{
-  /// highlights text
-  static char highint[5];
-  /// low intensity text
-  static char halfint[5];
-  /// normal intensity text
-  static char normint[6];
-  /// resets text properties
-  static char reset[5];
-  /// underlines text
-  static char underon[5];
-  /// underline off
-  static char underoff[6];
-  /// blue text
-  static char fgblue[6];
-  /// cyan text
-  static char fgcyan[6];
-  /// red text
-  static char fgred[6];
-  /// green text
-  static char fggreen[6];
-  /// default text
-  static char fgdef[6];
-  //@}
-
   ///@name JSBSim Messaging functions
   //@{
   /** Places a Message structure on the Message queue.
@@ -171,7 +203,7 @@ class JSBSIM_API FGJSBBase {
   void PutMessage(const std::string& text, double dVal);
   /** Reads the message on the queue (but does not delete it).
       @return 1 if some messages */
-  int SomeMessages(void) const { return !Messages.empty(); }
+  int SomeMessages(void) const { return !gdata().Messages.empty(); }
   /** Reads the message on the queue and removes it from the queue.
       This function also prints out the message.*/
   void ProcessMessage(void);
@@ -188,8 +220,6 @@ class JSBSIM_API FGJSBBase {
   /// Disables highlighting in the console output.
   void disableHighLighting(void);
 
-  static short debug_lvl;
-
   /** Converts from degrees Kelvin to degrees Fahrenheit.
   *   @param kelvin The temperature in degrees Kelvin.
   *   @return The temperature in Fahrenheit. */
@@ -337,14 +367,11 @@ class JSBSIM_API FGJSBBase {
 
   static constexpr double sign(double num) {return num>=0.0?1.0:-1.0;}
 
-  static double GaussianRandomNumber(void);
+  double GaussianRandomNumber(void);
 
 protected:
-  static Message localMsg;
-
-  static std::queue <Message> Messages;
-
-  static unsigned int messageId;
+  // Reference to the common data
+  CommonData _gdata;
 
   static constexpr double radtodeg = 180. / M_PI;
   static constexpr double degtorad = M_PI / 180.;
@@ -373,7 +400,6 @@ class JSBSIM_API FGJSBBase {
 
   static std::string CreateIndexedPropertyName(const std::string& Property, int index);
 
-  static int gaussian_random_number_phase;
 
 public:
 /// Moments L, M, N
diff --git a/src/JSBSim.cpp b/src/JSBSim.cpp
index f1b3977eda..d438becb64 100644
--- a/src/JSBSim.cpp
+++ b/src/JSBSim.cpp
@@ -481,9 +481,9 @@ int real_main(int argc, char* argv[])
     }
   }
   
-  cout << endl << JSBSim::FGFDMExec::fggreen << JSBSim::FGFDMExec::highint
+  cout << endl << FDMExec->gdata().fggreen <<  FDMExec->gdata().highint
        << "---- JSBSim Execution beginning ... --------------------------------------------"
-       << JSBSim::FGFDMExec::reset << endl << endl;
+       <<  FDMExec->gdata().reset << endl << endl;
 
   result = FDMExec->Run();  // MAKE AN INITIAL RUN
 
diff --git a/src/initialization/FGInitialCondition.cpp b/src/initialization/FGInitialCondition.cpp
index 3f5935935d..d41b7730ae 100644
--- a/src/initialization/FGInitialCondition.cpp
+++ b/src/initialization/FGInitialCondition.cpp
@@ -57,7 +57,8 @@ namespace JSBSim {
 
 //******************************************************************************
 
-FGInitialCondition::FGInitialCondition(FGFDMExec *FDMExec) : fdmex(FDMExec)
+FGInitialCondition::FGInitialCondition(FGFDMExec *FDMExec)
+  : FGJSBBase(FDMExec->gdata()), position(FDMExec->gdata()), orientation(FDMExec->gdata()), fdmex(FDMExec)
 {
   InitializeIC();
 
@@ -101,7 +102,7 @@ void FGInitialCondition::ResetIC(double u0, double v0, double w0,
   lastLatitudeSet = setgeoc;
   lastAltitudeSet = setagl;
 
-  orientation = FGQuaternion(phi0, theta0, psi0);
+  orientation = FGQuaternion(gdata(), phi0, theta0, psi0);
   const FGMatrix33& Tb2l = orientation.GetTInv();
 
   vUVW_NED = Tb2l * FGColumnVector3(u0, v0, w0);
@@ -130,7 +131,7 @@ void FGInitialCondition::InitializeIC(void)
 
   position.SetPositionGeodetic(0.0, 0.0, 0.0);
 
-  orientation = FGQuaternion(0.0, 0.0, 0.0);
+  orientation = FGQuaternion(gdata(), 0.0, 0.0, 0.0);
   vUVW_NED.InitMatrix();
   vPQR_body.InitMatrix();
   vt=0;
@@ -370,7 +371,7 @@ void FGInitialCondition::calcThetaBeta(double alfa, const FGColumnVector3& _vt_N
   double sinTheta = (v1xz * v0xz)(eY);
   vOrient(eTht) = asin(sinTheta);
 
-  orientation = FGQuaternion(vOrient);
+  orientation = FGQuaternion(gdata(), vOrient);
 
   const FGMatrix33& Tl2b = orientation.GetT();
   FGColumnVector3 v2 = Talpha * Tl2b * _vt_NED;
@@ -436,7 +437,7 @@ void FGInitialCondition::SetBetaRadIC(double bta)
   double sinTheta = (v2xz * vfxz)(eY);
   vOrient(eTht) = -asin(sinTheta);
 
-  orientation = FGQuaternion(vOrient);
+  orientation = FGQuaternion(gdata(), vOrient);
 }
 
 //******************************************************************************
@@ -452,7 +453,7 @@ void FGInitialCondition::SetEulerAngleRadIC(int idx, double angle)
   FGColumnVector3 vOrient = orientation.GetEuler();
 
   vOrient(idx) = angle;
-  orientation = FGQuaternion(vOrient);
+  orientation = FGQuaternion(gdata(), vOrient);
 
   if ((lastSpeedSet != setned) && (lastSpeedSet != setvg)) {
     const FGMatrix33& newTb2l = orientation.GetTInv();
@@ -663,7 +664,7 @@ double FGInitialCondition::GetAltitudeASLFtIC(void) const
 double FGInitialCondition::GetTerrainElevationFtIC(void) const
 {
   FGColumnVector3 normal, v, w;
-  FGLocation contact;
+  FGLocation contact(const_cast<CommonData&>(gdata()));
   double a = fdmex->GetInertial()->GetSemimajor();
   double b = fdmex->GetInertial()->GetSemiminor();
   contact.SetEllipse(a, b);
@@ -1144,7 +1145,7 @@ bool FGInitialCondition::Load_v1(Element* document)
   if (document->FindElement("psi"))
     vOrient(ePsi) = document->FindElementValueAsNumberConvertTo("psi", "RAD");
 
-  orientation = FGQuaternion(vOrient);
+  orientation = FGQuaternion(gdata(), vOrient);
 
   if (document->FindElement("ubody"))
     SetUBodyFpsIC(document->FindElementValueAsNumberConvertTo("ubody", "FT/SEC"));
@@ -1307,9 +1308,9 @@ bool FGInitialCondition::Load_v2(Element* document)
       //
       // Q_b/l = Q_i/l * Q_b/i
 
-      FGQuaternion QuatI2Body = FGQuaternion(vOrient);
+      FGQuaternion QuatI2Body = FGQuaternion(gdata(), vOrient);
       QuatI2Body.Normalize();
-      FGQuaternion QuatLocal2I = Tec2i * position.GetTl2ec();
+      FGQuaternion QuatLocal2I(gdata(), Tec2i * position.GetTl2ec());
       QuatLocal2I.Normalize();
       orientation = QuatLocal2I * QuatI2Body;
 
@@ -1325,20 +1326,20 @@ bool FGInitialCondition::Load_v2(Element* document)
       //
       // Q_b/l = Q_e/l * Q_b/e
 
-      FGQuaternion QuatEC2Body(vOrient); // Store relationship of Body frame wrt ECEF frame, Q_b/e
+      FGQuaternion QuatEC2Body(gdata(), vOrient); // Store relationship of Body frame wrt ECEF frame, Q_b/e
       QuatEC2Body.Normalize();
-      FGQuaternion QuatLocal2EC = position.GetTl2ec(); // Get Q_e/l from matrix
+      FGQuaternion QuatLocal2EC(gdata(), position.GetTl2ec()); // Get Q_e/l from matrix
       QuatLocal2EC.Normalize();
       orientation = QuatLocal2EC * QuatEC2Body; // Q_b/l = Q_e/l * Q_b/e
 
     } else if (frame == "local") {
 
-      orientation = FGQuaternion(vOrient);
+      orientation = FGQuaternion(gdata(), vOrient);
 
     } else {
 
-      cerr << endl << fgred << "  Orientation frame type: \"" << frame
-           << "\" is not supported!" << reset << endl << endl;
+      cerr << endl << gdata().fgred << "  Orientation frame type: \"" << frame
+           << "\" is not supported!" << gdata().reset << endl << endl;
       result = false;
 
     }
@@ -1377,8 +1378,8 @@ bool FGInitialCondition::Load_v2(Element* document)
       lastSpeedSet = setuvw;
     } else {
 
-      cerr << endl << fgred << "  Velocity frame type: \"" << frame
-           << "\" is not supported!" << reset << endl << endl;
+      cerr << endl << gdata().fgred << "  Velocity frame type: \"" << frame
+           << "\" is not supported!" << gdata().reset << endl << endl;
       result = false;
 
     }
@@ -1425,8 +1426,8 @@ bool FGInitialCondition::Load_v2(Element* document)
       vPQR_body = vAttRate;
     } else if (!frame.empty()) { // misspelling of frame
 
-      cerr << endl << fgred << "  Attitude rate frame type: \"" << frame
-           << "\" is not supported!" << reset << endl << endl;
+      cerr << endl << gdata().fgred << "  Attitude rate frame type: \"" << frame
+           << "\" is not supported!" << gdata().reset << endl << endl;
       result = false;
 
     } else if (frame.empty()) {
@@ -1608,6 +1609,7 @@ void FGInitialCondition::bind(FGPropertyManager* PropertyManager)
 
 void FGInitialCondition::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/initialization/FGTrim.cpp b/src/initialization/FGTrim.cpp
index 28cc75964f..d7f3d3ce03 100644
--- a/src/initialization/FGTrim.cpp
+++ b/src/initialization/FGTrim.cpp
@@ -59,7 +59,7 @@ namespace JSBSim {
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGTrim::FGTrim(FGFDMExec *FDMExec,TrimMode tt)
-  : fgic(FDMExec)
+  : FGJSBBase(FDMExec->gdata()), fgic(FDMExec)
 {
 
   Nsub=0;
@@ -78,13 +78,13 @@ FGTrim::FGTrim(FGFDMExec *FDMExec,TrimMode tt)
   targetNlf=fgic.GetTargetNlfIC();
   debug_axis=tAll;
   SetMode(tt);
-  if (debug_lvl & 2) cout << "Instantiated: FGTrim" << endl;
+  if (gdata().debug_lvl & 2) cout << "Instantiated: FGTrim" << endl;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGTrim::~FGTrim(void) {
-  if (debug_lvl & 2) cout << "Destroyed:    FGTrim" << endl;
+  if (gdata().debug_lvl & 2) cout << "Destroyed:    FGTrim" << endl;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -310,7 +310,7 @@ bool FGTrim::DoTrim(void) {
 
   if((!trim_failed) && (axis_count >= TrimAxes.size())) {
     total_its=N;
-    if (debug_lvl > 0)
+    if (gdata().debug_lvl > 0)
         cout << endl << "  Trim successful" << endl;
   } else { // The trim has failed
     total_its=N;
@@ -331,7 +331,7 @@ bool FGTrim::DoTrim(void) {
     if (fdmex->GetGroundReactions()->GetWOW())
       trimOnGround();
 
-    if (debug_lvl > 0)
+    if (gdata().debug_lvl > 0)
         cout << endl << "  Trim failed" << endl;
   }
 
@@ -396,7 +396,7 @@ void FGTrim::trimOnGround(void)
     FGLocation gearLoc = CGLocation.LocalToLocation(Tb2l * c.location);
 
     FGColumnVector3 normal, vDummy;
-    FGLocation lDummy;
+    FGLocation lDummy(gdata());
     double height = fdmex->GetInertial()->GetContactPoint(gearLoc, lDummy,
                                                           normal, vDummy,
                                                           vDummy);
@@ -439,7 +439,7 @@ void FGTrim::trimOnGround(void)
   // Compute the rotation parameters: angle and the first point to come into
   // contact with the ground when the rotation is applied.
   RotationParameters rParam = calcRotation(contacts, rotationAxis, contact0);
-  FGQuaternion q0(rParam.angleMin, rotationAxis);
+  FGQuaternion q0(gdata(), rParam.angleMin, rotationAxis);
 
   // Apply the computed rotation to all the contact points
   FGMatrix33 rot = q0.GetTInv();
@@ -465,7 +465,7 @@ void FGTrim::trimOnGround(void)
 
   // Compute the rotation parameters
   rParam = calcRotation(contacts, rotationAxis, contact0);
-  FGQuaternion q1(rParam.angleMin, rotationAxis);
+  FGQuaternion q1(gdata(), rParam.angleMin, rotationAxis);
 
   // Update the aircraft orientation
   FGColumnVector3 euler = (fgic.GetOrientation() * q0 * q1).GetEuler();
@@ -802,7 +802,7 @@ void FGTrim::SetMode(TrimMode tt) {
     mode=tt;
     switch(tt) {
       case tFull:
-        if (debug_lvl > 0)
+        if (gdata().debug_lvl > 0)
           cout << "  Full Trim" << endl;
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tWdot,tAlpha));
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tUdot,tThrottle ));
@@ -813,14 +813,14 @@ void FGTrim::SetMode(TrimMode tt) {
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tRdot,tRudder ));
         break;
       case tLongitudinal:
-        if (debug_lvl > 0)
+        if (gdata().debug_lvl > 0)
           cout << "  Longitudinal Trim" << endl;
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tWdot,tAlpha ));
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tUdot,tThrottle ));
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tQdot,tPitchTrim ));
         break;
       case tGround:
-        if (debug_lvl > 0)
+        if (gdata().debug_lvl > 0)
           cout << "  Ground Trim" << endl;
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tWdot,tAltAGL ));
         TrimAxes.push_back(FGTrimAxis(fdmex,&fgic,tQdot,tTheta ));
diff --git a/src/initialization/FGTrimAnalysis.cpp b/src/initialization/FGTrimAnalysis.cpp
index c5fc4f3a8c..9d8d22203b 100644
--- a/src/initialization/FGTrimAnalysis.cpp
+++ b/src/initialization/FGTrimAnalysis.cpp
@@ -318,6 +318,7 @@ void Objective::Set_x_val(double new_x)
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGTrimAnalysis::FGTrimAnalysis(FGFDMExec *FDMExec,TrimAnalysisMode tt)
+ : FGJSBBase(FDMExec->data())
 {
   SetDebug(2);
 
diff --git a/src/initialization/FGTrimAnalysisControl.cpp b/src/initialization/FGTrimAnalysisControl.cpp
index 53d37721df..806f476aaa 100644
--- a/src/initialization/FGTrimAnalysisControl.cpp
+++ b/src/initialization/FGTrimAnalysisControl.cpp
@@ -61,7 +61,8 @@ IDENT(IdHdr,ID_TRIMANALYSISCONTROL);
 
 FGTrimAnalysisControl::FGTrimAnalysisControl(FGFDMExec* fdex, FGInitialCondition* ic,
                                              //State st,
-                                             TaControl ctrl) {
+                                             TaControl ctrl)
+                                             : FGJSBBase(fdex->gdata()) {
   fdmex=fdex;
   fgic=ic;
   state=taAll;
diff --git a/src/initialization/FGTrimAxis.cpp b/src/initialization/FGTrimAxis.cpp
index f0e8298e12..2fbcc84bc0 100644
--- a/src/initialization/FGTrimAxis.cpp
+++ b/src/initialization/FGTrimAxis.cpp
@@ -59,7 +59,7 @@ namespace JSBSim {
 /*****************************************************************************/
 
 FGTrimAxis::FGTrimAxis(FGFDMExec* fdex, FGInitialCondition* ic, State st,
-                       Control ctrl) {
+                       Control ctrl) : FGJSBBase(fdex->gdata()) {
 
   fdmex=fdex;
   fgic=ic;
@@ -339,7 +339,7 @@ double FGTrimAxis::GetAvgStability( void ) {
 
 void FGTrimAxis::Debug(int from)
 {
-
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
   if (debug_lvl & 1 ) { // Standard console startup message output
     if (from == 0) { // Constructor
diff --git a/src/input_output/FGInputSocket.cpp b/src/input_output/FGInputSocket.cpp
index f5a9510e9b..53786efb83 100644
--- a/src/input_output/FGInputSocket.cpp
+++ b/src/input_output/FGInputSocket.cpp
@@ -96,7 +96,7 @@ bool FGInputSocket::InitModel(void)
 {
   if (FGInputType::InitModel()) {
     delete socket;
-    socket = new FGfdmSocket(SockPort, SockProtocol);
+    socket = new FGfdmSocket(gdata(), SockPort, SockProtocol);
 
     if (socket == 0) return false;
     if (!socket->GetConnectStatus()) return false;
diff --git a/src/input_output/FGInputType.cpp b/src/input_output/FGInputType.cpp
index 0522f5cc90..03da637935 100644
--- a/src/input_output/FGInputType.cpp
+++ b/src/input_output/FGInputType.cpp
@@ -38,6 +38,7 @@ INCLUDES
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 #include "FGInputType.h"
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -130,6 +131,7 @@ bool FGInputType::Run(bool Holding)
 
 void FGInputType::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message input
diff --git a/src/input_output/FGOutputSocket.cpp b/src/input_output/FGOutputSocket.cpp
index 0ad87af0d0..58cf3e5ea8 100644
--- a/src/input_output/FGOutputSocket.cpp
+++ b/src/input_output/FGOutputSocket.cpp
@@ -136,7 +136,7 @@ bool FGOutputSocket::InitModel(void)
 {
   if (FGOutputType::InitModel()) {
     delete socket;
-    socket = new FGfdmSocket(SockName, SockPort, SockProtocol, precision);
+    socket = new FGfdmSocket(gdata(), SockName, SockPort, SockProtocol, precision);
 
     if (socket == 0) return false;
     if (!socket->GetConnectStatus()) return false;
diff --git a/src/input_output/FGOutputTextFile.cpp b/src/input_output/FGOutputTextFile.cpp
index 073b9a0c96..e54f8548fb 100644
--- a/src/input_output/FGOutputTextFile.cpp
+++ b/src/input_output/FGOutputTextFile.cpp
@@ -86,10 +86,10 @@ bool FGOutputTextFile::OpenFile(void)
   datafile.clear();
   datafile.open(Filename);
   if (!datafile) {
-    cerr << endl << fgred << highint << "ERROR: unable to open the file "
-         << reset << Filename.c_str() << endl
-         << fgred << highint << "       => Output to this file is disabled."
-         << reset << endl << endl;
+    cerr << endl << gdata().fgred << gdata().highint << "ERROR: unable to open the file "
+         << gdata().reset << Filename.c_str() << endl
+         << gdata().fgred << gdata().highint << "       => Output to this file is disabled."
+         << gdata().reset << endl << endl;
     Disable();
     return false;
   }
diff --git a/src/input_output/FGOutputType.cpp b/src/input_output/FGOutputType.cpp
index 62465c617e..f885a51d23 100644
--- a/src/input_output/FGOutputType.cpp
+++ b/src/input_output/FGOutputType.cpp
@@ -135,10 +135,10 @@ bool FGOutputType::Load(Element* element)
     FGPropertyNode* node = PropertyManager->GetNode(property_str);
     if (!node) {
       cerr << property_element->ReadFrom()
-           << fgred << highint << endl << "  No property by the name "
+           << gdata().fgred << gdata().highint << endl << "  No property by the name "
            << property_str << " has been defined. This property will " << endl
            << "  not be logged. You should check your configuration file."
-           << reset << endl;
+           << gdata().reset << endl;
     } else {
       if (property_element->HasAttribute("apply")) {
         string function_str = property_element->GetAttributeValue("apply");
@@ -147,10 +147,10 @@ bool FGOutputType::Load(Element* element)
           OutputParameters.push_back(new FGFunctionValue(node, f));
         else {
           cerr << property_element->ReadFrom()
-               << fgred << highint << "  No function by the name "
+               << gdata().fgred << gdata().highint << "  No function by the name "
                << function_str << " has been defined. This property will "
                << "not be logged. You should check your configuration file."
-               << reset << endl;
+               << gdata().reset << endl;
         }
       }
       else
@@ -250,6 +250,7 @@ void FGOutputType::SetOutputProperties(vector<FGPropertyNode_ptr> & outputProper
 
 void FGOutputType::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/input_output/FGPropertyManager.cpp b/src/input_output/FGPropertyManager.cpp
index 9ec56b539f..761785b34c 100644
--- a/src/input_output/FGPropertyManager.cpp
+++ b/src/input_output/FGPropertyManager.cpp
@@ -318,7 +318,6 @@ void FGPropertyManager::Untie(SGPropertyNode *property)
     if (*it == property) {
       property->untie();
       tied_properties.erase(it);
-      if (FGJSBBase::debug_lvl & 0x20) cout << "Untied " << name << endl;
       return;
     }
   }
diff --git a/src/input_output/FGPropertyManager.h b/src/input_output/FGPropertyManager.h
index 12c78b4f62..271c66ee47 100644
--- a/src/input_output/FGPropertyManager.h
+++ b/src/input_output/FGPropertyManager.h
@@ -458,7 +458,6 @@ class JSBSIM_API FGPropertyManager
         cerr << "Failed to tie property " << name << " to a pointer" << endl;
       else {
         tied_properties.push_back(property);
-        if (FGJSBBase::debug_lvl & 0x20) cout << name << endl;
       }
     }
 
@@ -492,7 +491,6 @@ class JSBSIM_API FGPropertyManager
         if (!setter) property->setAttribute(SGPropertyNode::WRITE, false);
         if (!getter) property->setAttribute(SGPropertyNode::READ, false);
         tied_properties.push_back(property);
-        if (FGJSBBase::debug_lvl & 0x20) std::cout << name << std::endl;
       }
     }
 
@@ -529,7 +527,6 @@ class JSBSIM_API FGPropertyManager
         if (!setter) property->setAttribute(SGPropertyNode::WRITE, false);
         if (!getter) property->setAttribute(SGPropertyNode::READ, false);
         tied_properties.push_back(property);
-        if (FGJSBBase::debug_lvl & 0x20) std::cout << name << std::endl;
       }
     }
 
@@ -566,7 +563,6 @@ class JSBSIM_API FGPropertyManager
         if (!setter) property->setAttribute(SGPropertyNode::WRITE, false);
         if (!getter) property->setAttribute(SGPropertyNode::READ, false);
         tied_properties.push_back(property);
-        if (FGJSBBase::debug_lvl & 0x20) std::cout << name << std::endl;
       }
     }
 
@@ -604,7 +600,6 @@ class JSBSIM_API FGPropertyManager
         if (!setter) property->setAttribute(SGPropertyNode::WRITE, false);
         if (!getter) property->setAttribute(SGPropertyNode::READ, false);
         tied_properties.push_back(property);
-        if (FGJSBBase::debug_lvl & 0x20) std::cout << name << std::endl;
       }
    }
 
diff --git a/src/input_output/FGPropertyReader.cpp b/src/input_output/FGPropertyReader.cpp
index b4ca79826c..98dbc59075 100644
--- a/src/input_output/FGPropertyReader.cpp
+++ b/src/input_output/FGPropertyReader.cpp
@@ -67,14 +67,6 @@ bool FGPropertyReader::ResetToIC(void)
 void FGPropertyReader::Load(Element* el, FGPropertyManager* PM, bool override)
 {
   Element *property_element = el->FindElement("property");
-  if (property_element && FGJSBBase::debug_lvl > 0) {
-    cout << endl << "    ";
-    if (override)
-      cout << "Overriding";
-    else
-      cout << "Declared";
-    cout << " properties" << endl << endl;
-  }
 
   while (property_element) {
     SGPropertyNode* node = nullptr;
@@ -87,18 +79,6 @@ void FGPropertyReader::Load(Element* el, FGPropertyManager* PM, bool override)
       if (override) {
         node = PM->GetNode(interface_property_string);
 
-        if (FGJSBBase::debug_lvl > 0) {
-          if (interface_prop_initial_value.find(node) == interface_prop_initial_value.end()) {
-            cout << property_element->ReadFrom()
-                 << "  The following property will be overridden but it has not been" << endl
-                 << "  defined in the current model '" << el->GetName() << "'" << endl;
-          }
-
-          cout << "      " << "Overriding value for property " << interface_property_string << endl
-               << "       (old value: " << node->getDoubleValue() << "  new value: " << value << ")"
-               << endl << endl;
-        }
-
         node->setDoubleValue(value);
       }
       else {
@@ -112,10 +92,6 @@ void FGPropertyReader::Load(Element* el, FGPropertyManager* PM, bool override)
       node = PM->GetNode(interface_property_string, true);
       if (node) {
         node->setDoubleValue(value);
-
-        if (FGJSBBase::debug_lvl > 0)
-          cout << "      " << interface_property_string << " (initial value: " 
-               << value << ")" << endl << endl;
       }
       else {
         cerr << "Could not create property " << interface_property_string
diff --git a/src/input_output/FGScript.cpp b/src/input_output/FGScript.cpp
index fd5d309a7e..3ba12fe243 100644
--- a/src/input_output/FGScript.cpp
+++ b/src/input_output/FGScript.cpp
@@ -61,7 +61,7 @@ CLASS IMPLEMENTATION
 
 // Constructor
 
-FGScript::FGScript(FGFDMExec* fgex) : FDMExec(fgex)
+FGScript::FGScript(FGFDMExec* fgex) : FGJSBBase(fgex->gdata()), FDMExec(fgex)
 {
   PropertyManager=FDMExec->GetPropertyManager();
 
@@ -211,6 +211,7 @@ bool FGScript::LoadScript(const SGPath& script, double default_dT,
   }
 
   // Read local property/value declarations
+  auto& debug_lvl = gdata().debug_lvl;
   int saved_debug_lvl = debug_lvl;
   debug_lvl = 0; // Disable messages
   LocalProperties.Load(run_element, PropertyManager, true);
@@ -242,9 +243,9 @@ bool FGScript::LoadScript(const SGPath& script, double default_dT,
     Element* condition_element = event_element->FindElement("condition");
     if (condition_element != 0) {
       try {
-        newCondition = new FGCondition(condition_element, PropertyManager);
+        newCondition = new FGCondition(gdata(), condition_element, PropertyManager);
       } catch(string& str) {
-        cout << endl << fgred << str << reset << endl << endl;
+        cout << endl << gdata().fgred << str << gdata().reset << endl << endl;
         delete newEvent;
         return false;
       }
@@ -287,10 +288,10 @@ bool FGScript::LoadScript(const SGPath& script, double default_dT,
             newEvent->NotifyProperties.push_back(new FGFunctionValue(notifyPropertyName, PropertyManager, f));
           else {
             cerr << notify_property_element->ReadFrom()
-              << fgred << highint << "  No function by the name "
+              << gdata().fgred << gdata().highint << "  No function by the name "
               << function_str << " has been defined. This property will "
               << "not be logged. You should check your configuration file."
-              << reset << endl;
+              << gdata().reset << endl;
           }
         }
         else
@@ -494,10 +495,10 @@ bool FGScript::RunScript(void)
           cout << "  <b>" << thisEvent.Name << " (Event " << event_ctr << ")"
                << " executed at time: " << currentTime << "</b><br/>" << endl;
         } else  {
-          cout << endl << underon
-               << highint << thisEvent.Name << normint << underoff
+          cout << endl <<gdata().underon
+               << gdata().highint << thisEvent.Name << gdata().normint << gdata().underoff
                << " (Event " << event_ctr << ")"
-               << " executed at time: " << highint << currentTime << normint
+               << " executed at time: " << gdata().highint << currentTime << gdata().normint
                << endl;
         }
         if (!thisEvent.Description.empty()) {
@@ -555,6 +556,7 @@ bool FGScript::RunScript(void)
 
 void FGScript::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
@@ -601,7 +603,7 @@ void FGScript::Debug(int from)
                 stringstream s;
                 s << "  An attempt has been made to access a non-existent property" << endl
                   << "  in this event. Please check the property names used, spelling, etc.";
-                cerr << fgred << highint << endl << s.str() << reset << endl;
+                cerr << gdata().fgred << gdata().highint << endl << s.str() << gdata().reset << endl;
                 throw BaseException(s.str());
               } else {
                 cout << endl << "      set " << Events[i].SetParamName[j]
@@ -618,7 +620,7 @@ void FGScript::Debug(int from)
                 stringstream s;
                 s << "  An attempt has been made to access a non-existent property" << endl
                   << "  in this event. Please check the property names used, spelling, etc.";
-                cerr << fgred << highint << endl << s.str() << reset << endl;
+                cerr << gdata().fgred << gdata().highint << endl << s.str() << gdata().reset << endl;
                 throw BaseException(s.str());
               } else {
                 cout << endl << "      set " << Events[i].SetParamName[j]
diff --git a/src/input_output/FGUDPInputSocket.cpp b/src/input_output/FGUDPInputSocket.cpp
index ecf520c6bd..e3361c3ea2 100644
--- a/src/input_output/FGUDPInputSocket.cpp
+++ b/src/input_output/FGUDPInputSocket.cpp
@@ -76,8 +76,8 @@ bool FGUDPInputSocket::Load(Element* el)
     string property_str = property_element->GetDataLine();
     FGPropertyNode* node = PropertyManager->GetNode(property_str);
     if (!node) {
-      cerr << fgred << highint << endl << "  No property by the name "
-           << property_str << " can be found." << reset << endl;
+      cerr << gdata().fgred << gdata().highint << endl << "  No property by the name "
+           << property_str << " can be found." << gdata().reset << endl;
     } else {
       InputProperties.push_back(node);
     }
diff --git a/src/input_output/FGXMLElement.cpp b/src/input_output/FGXMLElement.cpp
index 094735d8ad..02cf1a17bf 100644
--- a/src/input_output/FGXMLElement.cpp
+++ b/src/input_output/FGXMLElement.cpp
@@ -32,6 +32,7 @@ INCLUDES
 #include <stdexcept>  // using domain_error, invalid_argument, and length_error.
 #include "FGXMLElement.h"
 #include "FGJSBBase.h"
+#include <random>
 
 using namespace std;
 
@@ -667,9 +668,12 @@ double Element::DisperseValue(Element *e, double val, const std::string& supplie
     if (!supplied_units.empty()) disp *= convert[supplied_units][target_units];
     string attType = e->GetAttributeValue("type");
     if (attType == "gaussian" || attType == "gaussiansigned") {
-      double grn = FGJSBBase::GaussianRandomNumber();
-    if (attType == "gaussian") {
-      value = val + disp*grn;
+      std::random_device rd{};
+      std::mt19937 gen{rd()};
+      std::normal_distribution<double> d{0, 1};
+      double grn = d(gen);
+      if (attType == "gaussian") {
+        value = val + disp*grn;
       } else { // Assume gaussiansigned
         value = (val + disp*grn)*(fabs(grn)/grn);
       }
@@ -755,13 +759,6 @@ void Element::MergeAttributes(Element* el)
   for (it=el->attributes.begin(); it != el->attributes.end(); ++it) {
     if (attributes.find(it->first) == attributes.end())
       attributes[it->first] = it->second;
-    else {
-      if (FGJSBBase::debug_lvl > 0 && (attributes[it->first] != it->second))
-        cout << el->ReadFrom() << " Attribute '" << it->first << "' is overridden in file "
-             << GetFileName() << ": line " << GetLineNumber() << endl
-             << " The value '" << attributes[it->first] << "' will be used instead of '"
-             << it->second << "'." << endl;
-    }
   }
 }
 
diff --git a/src/input_output/FGfdmSocket.cpp b/src/input_output/FGfdmSocket.cpp
index e6ebc91e14..761ac8e991 100644
--- a/src/input_output/FGfdmSocket.cpp
+++ b/src/input_output/FGfdmSocket.cpp
@@ -74,14 +74,15 @@ static bool LoadWinSockDLL(int debug_lvl)
     return false;
   }
 
-  if (debug_lvl > 0)
+  if (gdata().debug_lvl > 0)
     cout << "Winsock DLL loaded ..." << endl;
 
   return true;
 }
 #endif
 
-FGfdmSocket::FGfdmSocket(const string& address, int port, int protocol, int precision)
+FGfdmSocket::FGfdmSocket(CommonData& c, const string& address, int port, int protocol, int precision)
+  : FGJSBBase(c)
 {
   sckt = sckt_in = 0;
   Protocol = (ProtocolType)protocol;
@@ -90,7 +91,7 @@ FGfdmSocket::FGfdmSocket(const string& address, int port, int protocol, int prec
   this->precision = precision;
 
   #if defined(_MSC_VER) || defined(__MINGW32__)
-  if (!LoadWinSockDLL(debug_lvl)) return;
+  if (!LoadWinSockDLL(gdata().debug_lvl)) return;
   #endif
 
   struct addrinfo hints;
@@ -123,7 +124,7 @@ FGfdmSocket::FGfdmSocket(const string& address, int port, int protocol, int prec
 
   sckt = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
 
-  if (debug_lvl > 0) {
+  if (gdata().debug_lvl > 0) {
     if (protocol == ptUDP)  //use udp protocol
       cout << "Creating UDP socket on port " << port << endl;
     else //use tcp protocol
@@ -136,7 +137,7 @@ FGfdmSocket::FGfdmSocket(const string& address, int port, int protocol, int prec
     scktName.sin_port = htons(port);
 
     if (connect(sckt, (struct sockaddr*)&scktName, len) == 0) {   // successful
-      if (debug_lvl > 0)
+      if (gdata().debug_lvl > 0)
         cout << "Successfully connected to socket for output ..." << endl;
       connected = true;
     } else                // unsuccessful
@@ -151,7 +152,8 @@ FGfdmSocket::FGfdmSocket(const string& address, int port, int protocol, int prec
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 // assumes TCP or UDP socket on localhost, for inbound datagrams
-FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)
+FGfdmSocket::FGfdmSocket(CommonData& c, int port, int protocol, int precision)
+  : FGJSBBase(c)
 {
   sckt = -1;
   connected = false;
@@ -160,7 +162,7 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)
   this->precision = precision;
 
 #if defined(_MSC_VER) || defined(__MINGW32__)
-  if (!LoadWinSockDLL(debug_lvl)) return;
+  if (!LoadWinSockDLL(gdata().debug_lvl)) return;
 #endif
 
   if (Protocol == ptUDP) {  //use udp protocol
@@ -178,7 +180,7 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)
     sckt = socket(AF_INET, SOCK_STREAM, 0);
   }
 
-  if (debug_lvl > 0)
+  if (gdata().debug_lvl > 0)
     cout << "Creating input " << ProtocolName << " socket on port " << port
          << endl;
 
@@ -192,7 +194,7 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)
 
     int len = sizeof(struct sockaddr_in);
     if (bind(sckt, (struct sockaddr*)&scktName, len) != -1) {
-      if (debug_lvl > 0)
+      if (gdata().debug_lvl > 0)
         cout << "Successfully bound to " << ProtocolName
              << " input socket on port " << port << endl << endl;
 
@@ -415,6 +417,7 @@ void FGfdmSocket::WaitUntilReadable(void)
 
 void FGfdmSocket::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/input_output/FGfdmSocket.h b/src/input_output/FGfdmSocket.h
index 7327088df4..a901944c9d 100644
--- a/src/input_output/FGfdmSocket.h
+++ b/src/input_output/FGfdmSocket.h
@@ -70,8 +70,8 @@ CLASS DECLARATION
 class FGfdmSocket : public FGJSBBase
 {
 public:
-  FGfdmSocket(const std::string& address, int port, int protocol, int precision = 7);
-  FGfdmSocket(int port, int protocol, int precision = 7);
+  FGfdmSocket(CommonData& gdata, const std::string& address, int port, int protocol, int precision = 7);
+  FGfdmSocket(CommonData& gdata, int port, int protocol, int precision = 7);
   ~FGfdmSocket();
   void Send(void);
   void Send(const char *data, int length);
diff --git a/src/math/FGCondition.cpp b/src/math/FGCondition.cpp
index a98f1393ac..b9ef09ac2b 100644
--- a/src/math/FGCondition.cpp
+++ b/src/math/FGCondition.cpp
@@ -53,8 +53,8 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 // This constructor is called when tests are inside an element
-FGCondition::FGCondition(Element* element, FGPropertyManager* PropertyManager)
-  : Logic(elUndef), TestParam1(nullptr), TestParam2(nullptr),
+FGCondition::FGCondition(CommonData& c, Element* element, FGPropertyManager* PropertyManager)
+  : FGJSBBase(c), Logic(elUndef), TestParam1(nullptr), TestParam2(nullptr),
     Comparison(ecUndef)
 {
   InitializeConditionals();
@@ -74,7 +74,7 @@ FGCondition::FGCondition(Element* element, FGPropertyManager* PropertyManager)
 
   for (unsigned int i=0; i<element->GetNumDataLines(); i++) {
     string data = element->GetDataLine(i);
-    conditions.push_back(new FGCondition(data, PropertyManager, element));
+    conditions.push_back(new FGCondition(c, data, PropertyManager, element));
   }
 
   Element* condition_element = element->GetElement();
@@ -90,7 +90,7 @@ FGCondition::FGCondition(Element* element, FGPropertyManager* PropertyManager)
       throw std::invalid_argument("FGCondition: unrecognized tag:'" + tagName + "'");
     }
 
-    conditions.push_back(new FGCondition(condition_element, PropertyManager));
+    conditions.push_back(new FGCondition(c, condition_element, PropertyManager));
     condition_element = element->GetNextElement();
   }
 
@@ -101,9 +101,9 @@ FGCondition::FGCondition(Element* element, FGPropertyManager* PropertyManager)
 // This constructor is called when there are no nested test groups inside the
 // condition
 
-FGCondition::FGCondition(const string& test, FGPropertyManager* PropertyManager,
+FGCondition::FGCondition(CommonData& c, const string& test, FGPropertyManager* PropertyManager,
                          Element* el)
-  : Logic(elUndef), TestParam1(nullptr), TestParam2(nullptr),
+  : FGJSBBase(c), Logic(elUndef), TestParam1(nullptr), TestParam2(nullptr),
     Comparison(ecUndef)
 {
   InitializeConditionals();
@@ -279,6 +279,7 @@ void FGCondition::PrintCondition(string indent)
 
 void FGCondition::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/math/FGCondition.h b/src/math/FGCondition.h
index 517a4d8574..b57ed26846 100644
--- a/src/math/FGCondition.h
+++ b/src/math/FGCondition.h
@@ -66,14 +66,14 @@ CLASS DECLARATION
 class FGCondition : public FGJSBBase
 {
 public:
-  FGCondition(Element* element, FGPropertyManager* PropertyManager);
+  FGCondition(CommonData& c, Element* element, FGPropertyManager* PropertyManager);
   ~FGCondition(void);
 
   bool Evaluate(void);
   void PrintCondition(std::string indent="  ");
 
 private:
-  FGCondition(const std::string& test, FGPropertyManager* PropertyManager,
+  FGCondition(CommonData& c, const std::string& test, FGPropertyManager* PropertyManager,
               Element* el);
 
   enum eComparison {ecUndef=0, eEQ, eNE, eGT, eGE, eLT, eLE};
diff --git a/src/math/FGFunction.cpp b/src/math/FGFunction.cpp
index 0a777425ad..b4678b97ad 100644
--- a/src/math/FGFunction.cpp
+++ b/src/math/FGFunction.cpp
@@ -79,7 +79,7 @@ class aFunc: public FGFunction
   aFunc(const func_t& _f, FGFDMExec* fdmex, Element* el,
         const string& prefix, FGPropertyValue* v, unsigned int Nmax=Nmin,
         FGFunction::OddEven odd_even=FGFunction::OddEven::Either)
-    : FGFunction(fdmex->GetPropertyManager()), f(_f)
+    : FGFunction(fdmex->gdata(), fdmex->GetPropertyManager()), f(_f)
   {
     Load(el, v, fdmex, prefix);
     CheckMinArguments(el, Nmin);
@@ -109,14 +109,14 @@ template<typename func_t>
 class aFunc<func_t, 0>: public FGFunction
 {
 public:
-  aFunc(const func_t& _f, FGPropertyManager* pm, Element* el,
+  aFunc(CommonData& c, const func_t& _f, FGPropertyManager* pm, Element* el,
         const string& Prefix)
-    : FGFunction(pm), f(_f)
+    : FGFunction(c, pm), f(_f)
   {
     if (el->GetNumElements() != 0) {
       ostringstream buffer;
-      buffer << el->ReadFrom() << fgred << highint
-             << "<" << el->GetName() << "> should have no arguments." << reset
+      buffer << el->ReadFrom() << c.fgred << c.highint
+             << "<" << el->GetName() << "> should have no arguments." << c.reset
              << endl;
       throw WrongNumberOfArguments(buffer.str(), Parameters, el);
     }
@@ -157,9 +157,9 @@ bool GetBinary(double val, const string &ctxMsg)
   if (val < 1E-9) return false;
   else if (val-1 < 1E-9) return true;
   else {
-    cerr << ctxMsg << FGJSBBase::fgred << FGJSBBase::highint
+    cerr << ctxMsg
          << "Malformed conditional check in function definition."
-         << FGJSBBase::reset << endl;
+         << endl;
     throw("Fatal Error.");
   }
 }
@@ -191,11 +191,11 @@ FGParameter_ptr VarArgsFn(const func_t& _f, FGFDMExec* fdmex, Element* el,
   }
   catch(WrongNumberOfArguments& e) {
     if ((e.GetElement() == el) && (e.NumberOfArguments() == 1)) {
-      cerr << el->ReadFrom() << FGJSBBase::fgred
+      cerr << el->ReadFrom() << fdmex->gdata().fgred
            << "<" << el->GetName()
            << "> only has one argument which makes it a no-op." << endl
            << "Its argument will be evaluated but <" << el->GetName()
-           << "> will not be applied to the result." << FGJSBBase::reset << endl;
+           << "> will not be applied to the result." << fdmex->gdata().reset << endl;
       return e.FirstParameter();
     }
     else
@@ -207,7 +207,7 @@ FGParameter_ptr VarArgsFn(const func_t& _f, FGFDMExec* fdmex, Element* el,
 
 FGFunction::FGFunction(FGFDMExec* fdmex, Element* el, const string& prefix,
                        FGPropertyValue* var)
-  : FGFunction(fdmex->GetPropertyManager())
+  : FGFunction(fdmex->gdata(), fdmex->GetPropertyManager())
 {
   Load(el, var, fdmex, prefix);
   CheckMinArguments(el, 1);
@@ -220,8 +220,8 @@ FGFunction::FGFunction(FGFDMExec* fdmex, Element* el, const string& prefix,
       if (is_number(prefix))
         sCopyTo = replace(sCopyTo,"#",prefix);
       else {
-        cerr << el->ReadFrom() << fgred
-             << "Illegal use of the special character '#'" << reset << endl
+        cerr << el->ReadFrom() << gdata().fgred
+             << "Illegal use of the special character '#'" << gdata().reset << endl
              << "The 'copyto' argument in function " << Name << " is ignored."
              << endl;
         return;
@@ -230,9 +230,9 @@ FGFunction::FGFunction(FGFDMExec* fdmex, Element* el, const string& prefix,
 
     pCopyTo = PropertyManager->GetNode(sCopyTo);
     if (!pCopyTo)
-      cerr << el->ReadFrom() << fgred
+      cerr << el->ReadFrom() << gdata().fgred
            << "Property \"" << sCopyTo
-           << "\" must be previously defined in function " << Name << reset
+           << "\" must be previously defined in function " << Name << gdata().reset
            << "The 'copyto' argument is ignored." << endl;
   }
 }
@@ -243,9 +243,9 @@ void FGFunction::CheckMinArguments(Element* el, unsigned int _min)
 {
   if (Parameters.size() < _min) {
     ostringstream buffer;
-    buffer << el->ReadFrom() << fgred << highint
+    buffer << el->ReadFrom() << gdata().fgred << gdata().highint
            << "<" << el->GetName() << "> should have at least " << _min
-           << " argument(s)." << reset << endl;
+           << " argument(s)." << gdata().reset << endl;
     throw WrongNumberOfArguments(buffer.str(), Parameters, el);
   }
 }
@@ -256,9 +256,9 @@ void FGFunction::CheckMaxArguments(Element* el, unsigned int _max)
 {
   if (Parameters.size() > _max) {
     ostringstream buffer;
-    buffer << el->ReadFrom() << fgred << highint
+    buffer << el->ReadFrom() << gdata().fgred << gdata().highint
            << "<" << el->GetName() << "> should have no more than " << _max
-           << " argument(s)." << reset << endl;
+           << " argument(s)." << gdata().reset << endl;
     throw WrongNumberOfArguments(buffer.str(), Parameters, el);
   }
 }
@@ -271,17 +271,17 @@ void FGFunction::CheckOddOrEvenArguments(Element* el, OddEven odd_even)
   switch(odd_even) {
   case OddEven::Even:
     if (Parameters.size() % 2 == 1) {
-      cerr << el->ReadFrom() << fgred << highint
+      cerr << el->ReadFrom() << gdata().fgred << gdata().highint
            << "<" << el->GetName() << "> must have an even number of arguments."
-           << reset << endl;
+           << gdata().reset << endl;
       throw("Fatal Error");
     }
     break;
   case OddEven::Odd:
     if (Parameters.size() % 2 == 0) {
-      cerr << el->ReadFrom() << fgred << highint
+      cerr << el->ReadFrom() << gdata().fgred << gdata().highint
            << "<" << el->GetName() << "> must have an odd number of arguments."
-           << reset << endl;
+           << gdata().reset << endl;
       throw("Fatal Error");
     }
     break;
@@ -338,8 +338,8 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
           }
           else {
             cerr << element->ReadFrom()
-                 << fgred << "Illegal use of the special character '#'"
-                 << reset << endl;
+                 << gdata().fgred << "Illegal use of the special character '#'"
+                 << gdata().reset << endl;
             throw("Fatal Error.");
           }
         }
@@ -352,10 +352,10 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                                                      PropertyManager, f));
           else {
             cerr << element->ReadFrom()
-                 << fgred << highint << "  No function by the name "
+                 << gdata().fgred << gdata().highint << "  No function by the name "
                  << function_str << " has been defined. This property will "
                  << "not be logged. You should check your configuration file."
-                 << reset << endl;
+                 << gdata().reset << endl;
           }
         }
         else
@@ -374,7 +374,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                   << endl;
         throw BaseException("An internal table cannot be nested within a function.");
       }
-      Parameters.push_back(new FGTable(PropertyManager, element, Prefix));
+      Parameters.push_back(new FGTable(gdata(), PropertyManager, element, Prefix));
       // operations
     } else if (operation == "product") {
       auto f = [](const decltype(Parameters)& Parameters)->double {
@@ -611,8 +611,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       auto f = [generator, distribution]()->double {
                  return (*distribution.get())(*generator);
                };
-      Parameters.push_back(new aFunc<decltype(f), 0>(f, PropertyManager, element,
-                                                     Prefix));
+      Parameters.push_back(new aFunc<decltype(f), 0>(gdata(), f, PropertyManager, element, Prefix));
     } else if (operation == "urandom") {
       double lower = -1.0;
       double upper = 1.0;
@@ -627,16 +626,15 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       auto f = [generator, distribution]()->double {
                  return (*distribution.get())(*generator);
                };
-      Parameters.push_back(new aFunc<decltype(f), 0>(f, PropertyManager, element,
-                                                     Prefix));
+      Parameters.push_back(new aFunc<decltype(f), 0>(gdata(), f, PropertyManager, element, Prefix));
     } else if (operation == "switch") {
       string ctxMsg = element->ReadFrom();
-      auto f = [ctxMsg](const decltype(Parameters)& p)->double {
+      auto f = [this, ctxMsg](const decltype(Parameters)& p)->double {
                  double temp = p[0]->GetValue();
                  if (temp < 0.0) {
-                   cerr << ctxMsg << fgred << highint
+                   cerr << ctxMsg << gdata().fgred << gdata().highint
                         << "The switch function index (" << temp
-                        << ") is negative." << reset << endl;
+                        << ") is negative." << gdata().reset << endl;
                    throw("Fatal error");
                  }
                  size_t n = p.size()-1;
@@ -645,16 +643,15 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                  if (i < n)
                    return p[i+1]->GetValue();
                  else {
-                   cerr << ctxMsg << fgred << highint
+                   cerr << ctxMsg << gdata().fgred << gdata().highint
                         << "The switch function index (" << temp
                         << ") selected a value above the range of supplied values"
                         << "[0:" << n-1 << "]"
-                        << " - not enough values were supplied." << reset << endl;
+                        << " - not enough values were supplied." << gdata().reset << endl;
                    throw("Fatal error");
                  }
                };
-      Parameters.push_back(new aFunc<decltype(f), 2>(f, fdmex, element, Prefix,
-                                                     var, MaxArgs));
+      Parameters.push_back(new aFunc<decltype(f), 2>(f, fdmex, element, Prefix, var, MaxArgs));
     } else if (operation == "interpolate1d") {
       auto f = [](const decltype(Parameters)& p)->double {
                  // This is using the bisection algorithm. Special care has been
@@ -696,14 +693,14 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       // Calculates local angle of attack for skydiver body component.
       // Euler angles from the intermediate body frame to the local body frame
       // must be from a z-y-x axis rotation order
-      auto f = [](const decltype(Parameters)& p)->double {
+      auto f = [this](const decltype(Parameters)& p)->double {
                  double alpha = p[0]->GetValue()*degtorad; //angle of attack of intermediate body frame
                  double beta = p[1]->GetValue()*degtorad;  //sideslip angle of intermediate body frame
                  double phi = p[3]->GetValue()*degtorad;   //x-axis Euler angle from the intermediate body frame to the local body frame
                  double theta = p[4]->GetValue()*degtorad; //y-axis Euler angle from the intermediate body frame to the local body frame
                  double psi = p[5]->GetValue()*degtorad;   //z-axis Euler angle from the intermediate body frame to the local body frame
 
-                 FGQuaternion qTb2l(phi, theta, psi);
+                 FGQuaternion qTb2l(gdata(), phi, theta, psi);
                  double cos_beta = cos(beta);
                  FGColumnVector3 wind_body(cos(alpha)*cos_beta, sin(beta),
                                            sin(alpha)*cos_beta);
@@ -719,13 +716,13 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       // Calculates local angle of sideslip for skydiver body component.
       // Euler angles from the intermediate body frame to the local body frame
       // must be from a z-y-x axis rotation order
-      auto f = [](const decltype(Parameters)& p)->double {
+      auto f = [this](const decltype(Parameters)& p)->double {
                  double alpha = p[0]->GetValue()*degtorad; //angle of attack of intermediate body frame
                  double beta = p[1]->GetValue()*degtorad;  //sideslip angle of intermediate body frame
                  double phi = p[3]->GetValue()*degtorad;   //x-axis Euler angle from the intermediate body frame to the local body frame
                  double theta = p[4]->GetValue()*degtorad; //y-axis Euler angle from the intermediate body frame to the local body frame
                  double psi = p[5]->GetValue()*degtorad;   //z-axis Euler angle from the intermediate body frame to the local body frame
-                 FGQuaternion qTb2l(phi, theta, psi);
+                 FGQuaternion qTb2l(gdata(), phi, theta, psi);
                  double cos_beta = cos(beta);
                  FGColumnVector3 wind_body(cos(alpha)*cos_beta, sin(beta),
                                            sin(alpha)*cos_beta);
@@ -751,7 +748,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       // Calculates local roll angle for skydiver body component.
       // Euler angles from the intermediate body frame to the local body frame
       // must be from a z-y-x axis rotation order
-      auto f = [](const decltype(Parameters)& p)->double {
+      auto f = [this](const decltype(Parameters)& p)->double {
                  double alpha = p[0]->GetValue()*degtorad; //angle of attack of intermediate body frame
                  double beta = p[1]->GetValue()*degtorad;  //sideslip angle of intermediate body frame
                  double gamma = p[2]->GetValue()*degtorad; //roll angle of intermediate body frame
@@ -761,7 +758,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                  double cos_alpha = cos(alpha), sin_alpha = sin(alpha);
                  double cos_beta = cos(beta),   sin_beta = sin(beta);
                  double cos_gamma = cos(gamma), sin_gamma = sin(gamma);
-                 FGQuaternion qTb2l(phi, theta, psi);
+                 FGQuaternion qTb2l(gdata(), phi, theta, psi);
                  FGColumnVector3 wind_body_X(cos_alpha*cos_beta, sin_beta,
                                              sin_alpha*cos_beta);
                  FGColumnVector3 wind_body_Y(-sin_alpha*sin_gamma-sin_beta*cos_alpha*cos_gamma,
@@ -798,7 +795,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       // Transforms the input vector from a body frame to a wind frame. The
       // origin of the vector remains the same.
       string ctxMsg = element->ReadFrom();
-      auto f = [ctxMsg](const decltype(Parameters)& p)->double {
+      auto f = [this, ctxMsg](const decltype(Parameters)& p)->double {
                  double rx = p[0]->GetValue();             //x component of input vector
                  double ry = p[1]->GetValue();             //y component of input vector
                  double rz = p[2]->GetValue();             //z component of input vector
@@ -808,13 +805,13 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                  int idx = static_cast<int>(p[6]->GetValue());
 
                  if ((idx < 1) || (idx > 3)) {
-                   cerr << ctxMsg << fgred << highint
+                   cerr << ctxMsg << gdata().fgred << gdata().highint
                         << "The index must be one of the integer value 1, 2 or 3."
-                        << reset << endl;
+                        << gdata().reset << endl;
                    throw("Fatal error");
                  }
 
-                 FGQuaternion qa(eY, -alpha), qb(eZ, beta), qc(eX, -gamma);
+                 FGQuaternion qa(gdata(), eY, -alpha), qb(gdata(), eZ, beta), qc(gdata(), eX, -gamma);
                  FGMatrix33 mT = (qa*qb*qc).GetT();
                  FGColumnVector3 r0(rx, ry, rz);
                  FGColumnVector3 r = mT*r0;
@@ -826,7 +823,7 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
       // Transforms the input vector from q wind frame to a body frame. The
       // origin of the vector remains the same.
       string ctxMsg = element->ReadFrom();
-      auto f = [ctxMsg](const decltype(Parameters)& p)->double {
+      auto f = [this, ctxMsg](const decltype(Parameters)& p)->double {
                  double rx = p[0]->GetValue();             //x component of input vector
                  double ry = p[1]->GetValue();             //y component of input vector
                  double rz = p[2]->GetValue();             //z component of input vector
@@ -836,13 +833,13 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                  int idx = static_cast<int>(p[6]->GetValue());
 
                  if ((idx < 1) || (idx > 3)) {
-                   cerr << ctxMsg << fgred << highint
+                   cerr << ctxMsg << gdata().fgred << gdata().highint
                         << "The index must be one of the integer value 1, 2 or 3."
-                        << reset << endl;
+                        << gdata().reset << endl;
                    throw("Fatal error");
                  }
 
-                 FGQuaternion qa(eY, -alpha), qb(eZ, beta), qc(eX, -gamma);
+                 FGQuaternion qa(gdata(), eY, -alpha), qb(gdata(), eZ, beta), qc(gdata(), eX, -gamma);
                  FGMatrix33 mT = (qa*qb*qc).GetT();
                  FGColumnVector3 r0(rx, ry, rz);
                  mT.T();
@@ -852,9 +849,9 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
                };
       Parameters.push_back(new aFunc<decltype(f), 7>(f, fdmex, element, Prefix, var));
     } else if (operation != "description") {
-      cerr << element->ReadFrom() << fgred << highint
+      cerr << element->ReadFrom() << gdata().fgred << gdata().highint
            << "Bad operation <" << operation
-           << "> detected in configuration file" << reset << endl;
+           << "> detected in configuration file" << gdata().reset << endl;
     }
 
     // Optimize functions applied on constant parameters by replacing them by
@@ -869,8 +866,8 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
 
         Parameters.pop_back();
         Parameters.push_back(new FGRealValue(constant));
-        if (debug_lvl > 0)
-          cout << element->ReadFrom() << fggreen << highint
+        if (gdata().debug_lvl > 0)
+          cout << element->ReadFrom() << gdata().fggreen << gdata().highint
                << "<" << operation << "> is applied on constant parameters."
                << endl << "It will be replaced by its result ("
                << constant << ")";
@@ -878,11 +875,11 @@ void FGFunction::Load(Element* el, FGPropertyValue* var, FGFDMExec* fdmex,
         if (node) {
           node->setDoubleValue(constant);
           node->setAttribute(SGPropertyNode::WRITE, false);
-          if (debug_lvl > 0)
+          if (gdata().debug_lvl > 0)
             cout << " and the property " << pName
                  << " will be unbound and made read only.";
         }
-        cout << reset << endl << endl;
+        cout << gdata().reset << endl << endl;
       }
     }
     element = el->GetNextElement();
@@ -1017,6 +1014,7 @@ void FGFunction::bind(Element* el, const string& Prefix)
 
 void FGFunction::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/math/FGFunction.h b/src/math/FGFunction.h
index 873af1e3f4..30fc546852 100644
--- a/src/math/FGFunction.h
+++ b/src/math/FGFunction.h
@@ -753,12 +753,12 @@ class FGFunction : public FGParameter, public FGJSBBase
 {
 public:
   /// Default constructor.
-  FGFunction()
-    : cached(false), cachedValue(-HUGE_VAL), PropertyManager(nullptr),
+  FGFunction(CommonData& c)
+    : FGJSBBase(c), cached(false), cachedValue(-HUGE_VAL), PropertyManager(nullptr),
       pNode(nullptr), pCopyTo(nullptr) {}
 
-  explicit FGFunction(FGPropertyManager* pm)
-    : FGFunction()
+  explicit FGFunction(CommonData& c, FGPropertyManager* pm)
+    : FGFunction(c)
   { PropertyManager = pm; }
 
   /** Constructor.
diff --git a/src/math/FGLocation.cpp b/src/math/FGLocation.cpp
index 3db73ec1c3..b13ca1f703 100644
--- a/src/math/FGLocation.cpp
+++ b/src/math/FGLocation.cpp
@@ -51,8 +51,8 @@ namespace JSBSim {
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGLocation::FGLocation(void)
-  : mECLoc(1.0, 0.0, 0.0), mCacheValid(false)
+FGLocation::FGLocation(CommonData& r)
+  : FGJSBBase(r), mECLoc(1.0, 0.0, 0.0), mCacheValid(false)
 {
   e2 = c = 0.0;
   a = ec = ec2 = 1.0;
@@ -66,8 +66,8 @@ FGLocation::FGLocation(void)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGLocation::FGLocation(double lon, double lat, double radius)
-  : mCacheValid(false)
+FGLocation::FGLocation(CommonData& r, double lon, double lat, double radius)
+  : FGJSBBase(r), mCacheValid(false)
 {
   e2 = c = 0.0;
   a = ec = ec2 = 1.0;
@@ -89,8 +89,8 @@ FGLocation::FGLocation(double lon, double lat, double radius)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGLocation::FGLocation(const FGColumnVector3& lv)
-  : mECLoc(lv), mCacheValid(false)
+FGLocation::FGLocation(CommonData& r, const FGColumnVector3& lv)
+  : FGJSBBase(r), mECLoc(lv), mCacheValid(false)
 {
   e2 = c = 0.0;
   a = ec = ec2 = 1.0;
@@ -105,7 +105,7 @@ FGLocation::FGLocation(const FGColumnVector3& lv)
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGLocation::FGLocation(const FGLocation& l)
-  : mECLoc(l.mECLoc), mCacheValid(l.mCacheValid)
+  : FGJSBBase(const_cast<CommonData&>(l.gdata())), mECLoc(l.mECLoc), mCacheValid(l.mCacheValid)
 {
   a = l.a;
   e2 = l.e2;
diff --git a/src/math/FGLocation.h b/src/math/FGLocation.h
index ca4678016e..8866712c8d 100644
--- a/src/math/FGLocation.h
+++ b/src/math/FGLocation.h
@@ -152,20 +152,20 @@ class JSBSIM_API FGLocation : public FGJSBBase
 {
 public:
   /** Default constructor. */
-  FGLocation(void);
+  FGLocation(CommonData& c);
 
   /** Constructor to set the longitude, latitude and the distance
       from the center of the earth.
       @param lon longitude
       @param lat GEOCENTRIC latitude
       @param radius distance from center of earth to vehicle in feet*/
-  FGLocation(double lon, double lat, double radius);
+  FGLocation(CommonData& c, double lon, double lat, double radius);
 
   /** Constructor to initialize the location with the cartesian coordinates
       (X,Y,Z) contained in the input FGColumnVector3. Distances are in feet,
       the position is expressed in the ECEF frame.
       @param lv vector that contain the cartesian coordinates*/
-  FGLocation(const FGColumnVector3& lv);
+  FGLocation(CommonData& c, const FGColumnVector3& lv);
 
   /** Copy constructor. */
   FGLocation(const FGLocation& l);
@@ -324,7 +324,7 @@ class JSBSIM_API FGLocation : public FGJSBBase
       @param lvec Vector in the local horizontal coordinate frame
       @return The location in the earth centered and fixed frame */
   FGLocation LocalToLocation(const FGColumnVector3& lvec) const {
-    ComputeDerived(); return mTl2ec*lvec + mECLoc;
+    ComputeDerived(); return FGLocation(const_cast<CommonData&>(gdata()), mTl2ec*lvec + mECLoc);
   }
 
   /** Conversion from a location in the earth centered and fixed frame
@@ -448,7 +448,7 @@ class JSBSIM_API FGLocation : public FGJSBBase
       A new object is returned that defines a position which is the sum of the
       cartesian coordinates of the two positions provided. */
   FGLocation operator+(const FGLocation& l) const {
-    FGLocation result(mECLoc + l.mECLoc);
+    FGLocation result(const_cast<CommonData&>(gdata()), mECLoc + l.mECLoc);
     if (mEllipseSet) result.SetEllipse(a, ec*a);
     return result;
   }
@@ -457,7 +457,7 @@ class JSBSIM_API FGLocation : public FGJSBBase
       A new object is returned that defines a position which is the difference
       of the cartesian coordinates of the two positions provided. */
   FGLocation operator-(const FGLocation& l) const {
-    FGLocation result(mECLoc - l.mECLoc);
+    FGLocation result(const_cast<CommonData&>(gdata()), mECLoc - l.mECLoc);
     if (mEllipseSet) result.SetEllipse(a, ec*a);
     return result;
   }
@@ -467,7 +467,7 @@ class JSBSIM_API FGLocation : public FGJSBBase
       coordinates of the provided ECEF position scaled by the supplied scalar
       value. */
   FGLocation operator*(double scalar) const {
-    FGLocation result(scalar*mECLoc);
+    FGLocation result(const_cast<CommonData&>(gdata()), scalar*mECLoc);
     if (mEllipseSet) result.SetEllipse(a, ec*a);
     return result;
   }
diff --git a/src/math/FGMatrix33.cpp b/src/math/FGMatrix33.cpp
index bcf5105f14..7007bc6c44 100644
--- a/src/math/FGMatrix33.cpp
+++ b/src/math/FGMatrix33.cpp
@@ -103,9 +103,9 @@ string FGMatrix33::Dump(const string& delimiter, const string& prefix) const
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGQuaternion FGMatrix33::GetQuaternion(void) const
+FGQuaternion FGMatrix33::GetQuaternion(CommonData& c) const
 {
-  FGQuaternion Q;
+  FGQuaternion Q(c);
 
   double tempQ[4];
   int idx;
diff --git a/src/math/FGMatrix33.h b/src/math/FGMatrix33.h
index fce665356d..8c3cf6db37 100644
--- a/src/math/FGMatrix33.h
+++ b/src/math/FGMatrix33.h
@@ -254,7 +254,7 @@ class JSBSIM_API FGMatrix33
 
   /** Returns the quaternion associated with this direction cosine (rotation) matrix.
   */
-  FGQuaternion GetQuaternion(void) const;
+  FGQuaternion GetQuaternion(CommonData& c) const;
 
   /** Returns the Euler angle column vector associated with this matrix.
   */
diff --git a/src/math/FGModelFunctions.cpp b/src/math/FGModelFunctions.cpp
index 27891e14d2..86d01af3f3 100644
--- a/src/math/FGModelFunctions.cpp
+++ b/src/math/FGModelFunctions.cpp
@@ -54,7 +54,7 @@ FGModelFunctions::~FGModelFunctions()
   for (auto prefunc: PreFunctions) delete prefunc;
   for (auto postfunc: PostFunctions) delete postfunc;
 
-  if (debug_lvl & 2) cout << "Destroyed:    FGModelFunctions" << endl;
+  if (gdata().debug_lvl & 2) cout << "Destroyed:    FGModelFunctions" << endl;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/src/math/FGModelFunctions.h b/src/math/FGModelFunctions.h
index a19ba248ec..3f764de6ab 100644
--- a/src/math/FGModelFunctions.h
+++ b/src/math/FGModelFunctions.h
@@ -72,6 +72,7 @@ DECLARATION: FGModelFunctions
 class FGModelFunctions : public FGJSBBase
 {
 public:
+  FGModelFunctions(CommonData& c) : FGJSBBase(c) {}
   virtual ~FGModelFunctions();
   void RunPreFunctions(void);
   void RunPostFunctions(void);
diff --git a/src/math/FGQuaternion.cpp b/src/math/FGQuaternion.cpp
index 1895423c62..dc2d480657 100644
--- a/src/math/FGQuaternion.cpp
+++ b/src/math/FGQuaternion.cpp
@@ -61,7 +61,8 @@ namespace JSBSim {
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 // Initialize from q
-FGQuaternion::FGQuaternion(const FGQuaternion& q) : mCacheValid(q.mCacheValid)
+FGQuaternion::FGQuaternion(const FGQuaternion& q)
+  : FGJSBBase(const_cast<CommonData&>(q.gdata())), mCacheValid(q.mCacheValid)
 {
   data[0] = q(1);
   data[1] = q(2);
@@ -79,14 +80,14 @@ FGQuaternion::FGQuaternion(const FGQuaternion& q) : mCacheValid(q.mCacheValid)
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 // Initialize with the three euler angles
-FGQuaternion::FGQuaternion(double phi, double tht, double psi): mCacheValid(false)
+FGQuaternion::FGQuaternion(CommonData& c, double phi, double tht, double psi): FGJSBBase(c), mCacheValid(false)
 {
   InitializeFromEulerAngles(phi, tht, psi);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGQuaternion::FGQuaternion(FGColumnVector3 vOrient): mCacheValid(false)
+FGQuaternion::FGQuaternion(CommonData& c, FGColumnVector3 vOrient) : FGJSBBase(c), mCacheValid(false)
 {
   double phi = vOrient(ePhi);
   double tht = vOrient(eTht);
@@ -136,7 +137,7 @@ void FGQuaternion::InitializeFromEulerAngles(double phi, double tht, double psi)
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 // Initialize with a direction cosine (rotation) matrix
 
-FGQuaternion::FGQuaternion(const FGMatrix33& m) : mCacheValid(false)
+FGQuaternion::FGQuaternion(CommonData& c, const FGMatrix33& m) : FGJSBBase(c), mCacheValid(false)
 {
   data[0] = 0.50*sqrt(1.0 + m(1,1) + m(2,2) + m(3,3));
   double t = 0.25/data[0];
@@ -157,7 +158,7 @@ FGQuaternion::FGQuaternion(const FGMatrix33& m) : mCacheValid(false)
 */
 FGQuaternion FGQuaternion::GetQDot(const FGColumnVector3& PQR) const
 {
-  return FGQuaternion(
+  return FGQuaternion(const_cast<CommonData&>(gdata()),
     -0.5*( data[1]*PQR(eP) + data[2]*PQR(eQ) + data[3]*PQR(eR)),
      0.5*( data[0]*PQR(eP) - data[3]*PQR(eQ) + data[2]*PQR(eR)),
      0.5*( data[3]*PQR(eP) + data[0]*PQR(eQ) - data[1]*PQR(eR)),
diff --git a/src/math/FGQuaternion.h b/src/math/FGQuaternion.h
index f084a84b90..49ad90eb2c 100644
--- a/src/math/FGQuaternion.h
+++ b/src/math/FGQuaternion.h
@@ -87,7 +87,7 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
 public:
   /** Default initializer.
       Default initializer, initializes the class with the identity rotation.  */
-  FGQuaternion() : mCacheValid(false) {
+  FGQuaternion(CommonData& c) : FGJSBBase(c), mCacheValid(false) {
     data[0] = 1.0;
     data[1] = data[2] = data[3] = 0.0;
   }
@@ -102,20 +102,20 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       @param phi The euler X axis (roll) angle in radians
       @param tht The euler Y axis (attitude) angle in radians
       @param psi The euler Z axis (heading) angle in radians  */
-  FGQuaternion(double phi, double tht, double psi);
+  FGQuaternion(CommonData& c, double phi, double tht, double psi);
 
   /** Initializer by euler angle vector.
       Initialize the quaternion with the euler angle vector.
       @param vOrient The euler axis angle vector in radians (phi, tht, psi) */
-  FGQuaternion(FGColumnVector3 vOrient);
+  FGQuaternion(CommonData& c, FGColumnVector3 vOrient);
 
   /** Initializer by one euler angle.
       Initialize the quaternion with the single euler angle where its index
       is given in the first argument.
       @param idx Index of the euler angle to initialize
       @param angle The euler angle in radians  */
-  FGQuaternion(int idx, double angle)
-    : mCacheValid(false) {
+  FGQuaternion(CommonData& c, int idx, double angle)
+    : FGJSBBase(c), mCacheValid(false) {
 
     double angle2 = 0.5*angle;
 
@@ -149,8 +149,8 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       @param angle The angle in radians
       @param axis  The rotation axis
    */
-  FGQuaternion(double angle, const FGColumnVector3& axis)
-    : mCacheValid(false) {
+  FGQuaternion(CommonData& c, double angle, const FGColumnVector3& axis)
+    : FGJSBBase(c), mCacheValid(false) {
 
     double angle2 = 0.5 * angle;
 
@@ -168,7 +168,7 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       Initialize the quaternion with the matrix representing a transform from one frame
       to another using the standard aerospace sequence, Yaw-Pitch-Roll (3-2-1).
       @param m the rotation matrix */
-  FGQuaternion(const FGMatrix33& m);
+  FGQuaternion(CommonData& c, const FGMatrix33& m);
 
   /// Destructor.
   ~FGQuaternion() {}
@@ -387,7 +387,8 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       @param q a quaternion to be summed.
       @return a quaternion representing Q, where Q = Q + q. */
   FGQuaternion operator+(const FGQuaternion& q) const {
-    return FGQuaternion(data[0]+q.data[0], data[1]+q.data[1],
+    return FGQuaternion(const_cast<CommonData&>(gdata()),
+                        data[0]+q.data[0], data[1]+q.data[1],
                         data[2]+q.data[2], data[3]+q.data[3]);
   }
 
@@ -395,7 +396,8 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       @param q a quaternion to be subtracted.
       @return a quaternion representing Q, where Q = Q - q. */
   FGQuaternion operator-(const FGQuaternion& q) const {
-    return FGQuaternion(data[0]-q.data[0], data[1]-q.data[1],
+    return FGQuaternion(const_cast<CommonData&>(gdata()),
+                        data[0]-q.data[0], data[1]-q.data[1],
                         data[2]-q.data[2], data[3]-q.data[3]);
   }
 
@@ -404,7 +406,8 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       @param q a quaternion to be multiplied.
       @return a quaternion representing Q, where Q = Q * q. */
   FGQuaternion operator*(const FGQuaternion& q) const {
-    return FGQuaternion(data[0]*q.data[0]-data[1]*q.data[1]-data[2]*q.data[2]-data[3]*q.data[3],
+    return FGQuaternion(const_cast<CommonData&>(gdata()),
+                        data[0]*q.data[0]-data[1]*q.data[1]-data[2]*q.data[2]-data[3]*q.data[3],
                         data[0]*q.data[1]+data[1]*q.data[0]+data[2]*q.data[3]-data[3]*q.data[2],
                         data[0]*q.data[2]-data[1]*q.data[3]+data[2]*q.data[0]+data[3]*q.data[1],
                         data[0]*q.data[3]+data[1]*q.data[2]-data[2]*q.data[1]+data[3]*q.data[0]);
@@ -438,7 +441,8 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
     if (norm == 0.0)
       return *this;
     double rNorm = 1.0/norm;
-    return FGQuaternion( data[0]*rNorm, -data[1]*rNorm,
+    return FGQuaternion(const_cast<CommonData&>(gdata()),
+                        data[0]*rNorm, -data[1]*rNorm,
                          -data[2]*rNorm, -data[3]*rNorm );
   }
 
@@ -448,7 +452,7 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
       to the inverse iff the quaternion is normalized.
   */
   FGQuaternion Conjugate(void) const {
-    return FGQuaternion( data[0], -data[1], -data[2], -data[3] );
+    return FGQuaternion(const_cast<CommonData&>(gdata()), data[0], -data[1], -data[2], -data[3] );
   }
 
   friend FGQuaternion operator*(double, const FGQuaternion&);
@@ -477,15 +481,15 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
 
   /** Zero quaternion vector. Does not represent any orientation.
       Useful for initialization of increments */
-  static FGQuaternion zero(void) { return FGQuaternion( 0.0, 0.0, 0.0, 0.0 ); }
+  static FGQuaternion zero(CommonData& c) { return FGQuaternion(c, 0.0, 0.0, 0.0, 0.0 ); }
 
   std::string Dump(const std::string& delimiter) const;
 
-  friend FGQuaternion QExp(const FGColumnVector3& omega);
+  friend FGQuaternion QExp(CommonData& c, const FGColumnVector3& omega);
 
 private:
   /** Copying by assigning the vector valued components.  */
-  FGQuaternion(double q1, double q2, double q3, double q4) : mCacheValid(false)
+  FGQuaternion(CommonData& c, double q1, double q2, double q3, double q4) : FGJSBBase(c), mCacheValid(false)
     { data[0] = q1; data[1] = q2; data[2] = q3; data[3] = q4; }
 
   /** Computation of derived values.
@@ -537,7 +541,7 @@ class JSBSIM_API FGQuaternion : public FGJSBBase {
     Multiply the Vector with a scalar value.
 */
 inline FGQuaternion operator*(double scalar, const FGQuaternion& q) {
-  return FGQuaternion(scalar*q.data[0], scalar*q.data[1], scalar*q.data[2], scalar*q.data[3]);
+  return FGQuaternion(const_cast<CommonData&>(q.gdata()), scalar*q.data[0], scalar*q.data[1], scalar*q.data[2], scalar*q.data[3]);
 }
 
 /** Quaternion exponential
@@ -545,8 +549,8 @@ inline FGQuaternion operator*(double scalar, const FGQuaternion& q) {
     Calculate the unit quaternion which is the result of the exponentiation of
     the vector 'omega'.
 */
-inline FGQuaternion QExp(const FGColumnVector3& omega) {
-  FGQuaternion qexp;
+inline FGQuaternion QExp(CommonData& c, const FGColumnVector3& omega) {
+  FGQuaternion qexp(c);
   double angle = omega.Magnitude();
   double sina_a = angle > 0.0 ? sin(angle)/angle : 1.0;
 
diff --git a/src/math/FGTable.cpp b/src/math/FGTable.cpp
index 10e7163d4a..ee45ae70df 100644
--- a/src/math/FGTable.cpp
+++ b/src/math/FGTable.cpp
@@ -50,8 +50,8 @@ namespace JSBSim {
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGTable::FGTable(int NRows)
-  : nRows(NRows), nCols(1), PropertyManager(nullptr)
+FGTable::FGTable(CommonData& c, int NRows)
+  : FGJSBBase(c), nRows(NRows), nCols(1), PropertyManager(nullptr)
 {
   Type = tt1D;
   // Fill unused elements with NaNs to detect illegal access.
@@ -62,8 +62,8 @@ FGTable::FGTable(int NRows)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGTable::FGTable(int NRows, int NCols)
-  : nRows(NRows), nCols(NCols), PropertyManager(nullptr)
+FGTable::FGTable(CommonData& c, int NRows, int NCols)
+  : FGJSBBase(c), nRows(NRows), nCols(NCols), PropertyManager(nullptr)
 {
   Type = tt2D;
   // Fill unused elements with NaNs to detect illegal access.
@@ -73,8 +73,8 @@ FGTable::FGTable(int NRows, int NCols)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGTable::FGTable(const FGTable& t)
-  : PropertyManager(t.PropertyManager)
+FGTable::FGTable(CommonData& c, const FGTable& t)
+  :  FGJSBBase(c), PropertyManager(t.PropertyManager)
 {
   Type = t.Type;
   nRows = t.nRows;
@@ -88,7 +88,7 @@ FGTable::FGTable(const FGTable& t)
   // Deep copy of t.Tables
   Tables.reserve(t.Tables.size());
   for(const auto &t: t.Tables)
-    Tables.push_back(std::unique_ptr<FGTable>(new FGTable(*t)));
+    Tables.push_back(std::unique_ptr<FGTable>(new FGTable(c, *t)));
 
   Data = t.Data;
 }
@@ -109,9 +109,9 @@ unsigned int FindNumColumns(const string& test_line)
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGTable::FGTable(FGPropertyManager* propMan, Element* el,
+FGTable::FGTable(CommonData& c, FGPropertyManager* propMan, Element* el,
                  const std::string& Prefix)
-  : PropertyManager(propMan)
+  : FGJSBBase(c), PropertyManager(propMan)
 {
   string brkpt_string;
   Element *tableData = nullptr;
@@ -142,10 +142,10 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
     // at the same time that independentVars are specified.
     if (internal) {
       cerr  << el->ReadFrom()
-            << fgred << "  This table specifies both 'internal' call type" << endl
+            << gdata().fgred << "  This table specifies both 'internal' call type" << endl
             << "  and specific lookup properties via the 'independentVar' element." << endl
             << "  These are mutually exclusive specifications. The 'internal'" << endl
-            << "  attribute will be ignored." << fgdef << endl << endl;
+            << "  attribute will be ignored." << gdata().fgdef << endl << endl;
       internal = false;
     }
 
@@ -326,7 +326,7 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
 
     tableData = el->FindElement("tableData");
     while (tableData) {
-      Tables.push_back(std::unique_ptr<FGTable>(new FGTable(PropertyManager, tableData)));
+      Tables.push_back(std::unique_ptr<FGTable>(new FGTable(gdata(), PropertyManager, tableData)));
       Data.push_back(tableData->GetAttributeValueAsNumber("breakPoint"));
       Tables.back()->lookupProperty[eRow] = lookupProperty[eRow];
       Tables.back()->lookupProperty[eColumn] = lookupProperty[eColumn];
@@ -354,11 +354,11 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
     for (unsigned int b=2; b<=Tables.size(); ++b) {
       if (Data[b] <= Data[b-1]) {
         std::cerr << el->ReadFrom()
-                  << fgred << highint
+                  << gdata().fgred << gdata().highint
                   << "  FGTable: breakpoint lookup is not monotonically increasing" << endl
                   << "  in breakpoint " << b;
         if (nameel != 0) std::cerr << " of table in " << nameel->GetAttributeValue("name");
-        std::cerr << ":" << reset << endl
+        std::cerr << ":" << gdata().reset << endl
                   << "  " << Data[b] << "<=" << Data[b-1] << endl;
         throw BaseException("Breakpoint lookup is not monotonically increasing");
       }
@@ -370,11 +370,11 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
     for (unsigned int c=2; c<=nCols; ++c) {
       if (Data[c] <= Data[c-1]) {
         std::cerr << el->ReadFrom()
-                  << fgred << highint
+                  << gdata().fgred << gdata().highint
                   << "  FGTable: column lookup is not monotonically increasing" << endl
                   << "  in column " << c;
         if (nameel != 0) std::cerr << " of table in " << nameel->GetAttributeValue("name");
-        std::cerr << ":" << reset << endl
+        std::cerr << ":" << gdata().reset << endl
                   << "  " << Data[c] << "<=" << Data[c-1] << endl;
         throw BaseException("FGTable: column lookup is not monotonically increasing");
       }
@@ -386,11 +386,11 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
     for (size_t r=2; r<=nRows; ++r) {
       if (Data[r*(nCols+1)]<=Data[(r-1)*(nCols+1)]) {
         std::cerr << el->ReadFrom()
-                  << fgred << highint
+                  << gdata().fgred << gdata().highint
                   << "  FGTable: row lookup is not monotonically increasing" << endl
                   << "  in row " << r;
         if (nameel != 0) std::cerr << " of table in " << nameel->GetAttributeValue("name");
-        std::cerr << ":" << reset << endl
+        std::cerr << ":" << gdata().reset << endl
                   << "  " << Data[r*(nCols+1)] << "<=" << Data[(r-1)*(nCols+1)] << endl;
         throw BaseException("FGTable: row lookup is not monotonically increasing");
       }
@@ -415,7 +415,7 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
 
   bind(el, Prefix);
 
-  if (debug_lvl & 1) Print();
+  if (gdata().debug_lvl & 1) Print();
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -423,10 +423,10 @@ FGTable::FGTable(FGPropertyManager* propMan, Element* el,
 void FGTable::missingData(Element *el, unsigned int expected_size, size_t actual_size)
 {
   std::cerr << el->ReadFrom()
-            << fgred << highint
+            << gdata().fgred << gdata().highint
             << "  FGTable: Missing data";
   if (!Name.empty()) std::cerr << " in table " << Name;
-  std::cerr << ":" << reset << endl
+  std::cerr << ":" << gdata().reset << endl
             << "  Expecting " << expected_size << " elements while "
             << actual_size << " elements were provided." << endl;
   throw BaseException("FGTable: missing data");
@@ -718,6 +718,7 @@ void FGTable::bind(Element* el, const string& Prefix)
 
 void FGTable::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/math/FGTable.h b/src/math/FGTable.h
index 2ac7aeeaa7..2798c5d84d 100644
--- a/src/math/FGTable.h
+++ b/src/math/FGTable.h
@@ -240,7 +240,7 @@ class JSBSIM_API FGTable : public FGParameter, public FGJSBBase
 
   /** This is the very important copy constructor.
       @param table a const reference to a table.*/
-  FGTable(const FGTable& table);
+  FGTable(CommonData& c, const FGTable& table);
   /// Copy assignment constructor.
   /* MSVC issues an error C2280 if not defined : it is needed by
      std::unique_ptr<FGTable>.
@@ -248,9 +248,9 @@ class JSBSIM_API FGTable : public FGParameter, public FGJSBBase
   FGTable& operator=(const FGTable&);
 
   /// The constructor for a table
-  FGTable (FGPropertyManager* propMan, Element* el, const std::string& prefix="");
-  FGTable (int );
-  FGTable (int, int);
+  FGTable (CommonData& c, FGPropertyManager* propMan, Element* el, const std::string& prefix="");
+  FGTable (CommonData& c, int );
+  FGTable (CommonData& c, int, int);
   double GetValue(void) const;
   double GetValue(double key) const;
   double GetValue(double rowKey, double colKey) const;
diff --git a/src/math/FGTemplateFunc.cpp b/src/math/FGTemplateFunc.cpp
index 07f95ba24c..1df1885e8a 100644
--- a/src/math/FGTemplateFunc.cpp
+++ b/src/math/FGTemplateFunc.cpp
@@ -48,7 +48,7 @@ namespace JSBSim {
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGTemplateFunc::FGTemplateFunc(FGFDMExec* fdmex, Element* element)
-  : FGFunction(fdmex->GetPropertyManager())
+  : FGFunction(fdmex->gdata(), fdmex->GetPropertyManager())
 {
   var = new FGPropertyValue(nullptr);
   Load(element, var, fdmex);
diff --git a/src/models/FGAccelerations.cpp b/src/models/FGAccelerations.cpp
index b0a50bcb64..c96aa5d436 100644
--- a/src/models/FGAccelerations.cpp
+++ b/src/models/FGAccelerations.cpp
@@ -403,6 +403,7 @@ void FGAccelerations::bind(void)
 
 void FGAccelerations::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGAerodynamics.cpp b/src/models/FGAerodynamics.cpp
index c98236a651..af0ecec84a 100644
--- a/src/models/FGAerodynamics.cpp
+++ b/src/models/FGAerodynamics.cpp
@@ -38,6 +38,7 @@ INCLUDES
 
 #include "FGAerodynamics.h"
 #include "input_output/FGXMLElement.h"
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -382,8 +383,8 @@ bool FGAerodynamics::Load(Element *document)
         ca.push_back( new FGFunction(FDMExec, function_element) );
       } catch (const string& str) {
         cerr << endl << axis_element->ReadFrom()
-             << endl << fgred << "Error loading aerodynamic function in "
-             << current_func_name << ":" << str << " Aborting." << reset << endl;
+             << endl << gdata().fgred << "Error loading aerodynamic function in "
+             << current_func_name << ":" << str << " Aborting." << gdata().reset << endl;
         return false;
       }
       } else {
@@ -391,8 +392,8 @@ bool FGAerodynamics::Load(Element *document)
           ca_atCG.push_back( new FGFunction(FDMExec, function_element) );
         } catch (const string& str) {
           cerr << endl << axis_element->ReadFrom()
-               << endl << fgred << "Error loading aerodynamic function in "
-               << current_func_name << ":" << str << " Aborting." << reset << endl;
+               << endl << gdata().fgred << "Error loading aerodynamic function in "
+               << current_func_name << ":" << str << " Aborting." << gdata().reset << endl;
           return false;
         }
       }
@@ -692,6 +693,7 @@ void FGAerodynamics::BuildStabilityTransformMatrices(void)
 
 void FGAerodynamics::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGAircraft.cpp b/src/models/FGAircraft.cpp
index cdd0703d4d..04b15cd313 100644
--- a/src/models/FGAircraft.cpp
+++ b/src/models/FGAircraft.cpp
@@ -40,6 +40,7 @@ INCLUDES
 
 #include "FGAircraft.h"
 #include "input_output/FGXMLElement.h"
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -218,6 +219,7 @@ void FGAircraft::bind(void)
 
 void FGAircraft::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGAtmosphere.cpp b/src/models/FGAtmosphere.cpp
index 219f9b68b5..8b93234fed 100644
--- a/src/models/FGAtmosphere.cpp
+++ b/src/models/FGAtmosphere.cpp
@@ -306,6 +306,7 @@ void FGAtmosphere::bind(void)
 
 void FGAtmosphere::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGAuxiliary.cpp b/src/models/FGAuxiliary.cpp
index 67c5b905fd..5ee320db64 100644
--- a/src/models/FGAuxiliary.cpp
+++ b/src/models/FGAuxiliary.cpp
@@ -57,7 +57,8 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 
-FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex)
+FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex)
+  : FGModel(fdmex), in(fdmex->gdata()), vLocationVRP(fdmex->gdata())
 {
   Name = "FGAuxiliary";
   pt = 2116.23; // ISA SL pressure
@@ -395,6 +396,7 @@ double FGAuxiliary::BadUnits(void) const
 
 void FGAuxiliary::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGAuxiliary.h b/src/models/FGAuxiliary.h
index f1e3fa1b34..4536003b9b 100644
--- a/src/models/FGAuxiliary.h
+++ b/src/models/FGAuxiliary.h
@@ -252,6 +252,7 @@ class JSBSIM_API FGAuxiliary : public FGModel {
   void SetAeroPQR(const FGColumnVector3& tt) { vAeroPQR = tt; }
 
   struct Inputs {
+    Inputs(CommonData& c) : vLocation(c) {}
     double Pressure;
     double Density;
     double DensitySL;
diff --git a/src/models/FGBuoyantForces.cpp b/src/models/FGBuoyantForces.cpp
index ec1dfe729f..c80b7e8a31 100644
--- a/src/models/FGBuoyantForces.cpp
+++ b/src/models/FGBuoyantForces.cpp
@@ -277,6 +277,7 @@ void FGBuoyantForces::bind(void)
 
 void FGBuoyantForces::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl; 
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGExternalForce.cpp b/src/models/FGExternalForce.cpp
index 81221b54d4..0173f3e499 100644
--- a/src/models/FGExternalForce.cpp
+++ b/src/models/FGExternalForce.cpp
@@ -223,6 +223,7 @@ const FGColumnVector3& FGExternalForce::GetBodyForces(void)
 
 void FGExternalForce::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGExternalReactions.cpp b/src/models/FGExternalReactions.cpp
index 4e28c31c58..5ee8af919b 100644
--- a/src/models/FGExternalReactions.cpp
+++ b/src/models/FGExternalReactions.cpp
@@ -39,6 +39,7 @@ INCLUDES
 #include "FGExternalForce.h"
 #include "FGExternalReactions.h"
 #include "input_output/FGXMLElement.h"
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -167,6 +168,7 @@ void FGExternalReactions::bind(void)
 
 void FGExternalReactions::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGFCS.cpp b/src/models/FGFCS.cpp
index 9409af82c2..4be9ab8069 100644
--- a/src/models/FGFCS.cpp
+++ b/src/models/FGFCS.cpp
@@ -166,7 +166,7 @@ bool FGFCS::Run(bool Holding)
 
   // Execute system channels in order
   for (i=0; i<SystemChannels.size(); i++) {
-    if (debug_lvl & 4) cout << "    Executing System Channel: " << SystemChannels[i]->GetName() << endl;
+    if (gdata().debug_lvl & 4) cout << "    Executing System Channel: " << SystemChannels[i]->GetName() << endl;
     ChannelRate = SystemChannels[i]->GetRate();
     SystemChannels[i]->Execute();
   }
@@ -506,10 +506,10 @@ bool FGFCS::Load(Element* document)
     if (sOnOffProperty.length() > 0) {
       FGPropertyNode* OnOffPropertyNode = PropertyManager->GetNode(sOnOffProperty);
       if (OnOffPropertyNode == 0) {
-        cerr << channel_element->ReadFrom() << highint << fgred
+        cerr << channel_element->ReadFrom() << gdata().highint << gdata().fgred
              << "The On/Off property, " << sOnOffProperty << " specified for channel "
              << channel_element->GetAttributeValue("name") << " is undefined or not "
-             << "understood. The simulation will abort" << reset << endl;
+             << "understood. The simulation will abort" << gdata().reset << endl;
         throw("Bad system definition");
       } else
         newChannel = new FGFCSChannel(this, sChannelName, ChannelRate,
@@ -519,9 +519,9 @@ bool FGFCS::Load(Element* document)
 
     SystemChannels.push_back(newChannel);
 
-    if (debug_lvl > 0)
-      cout << endl << highint << fgblue << "    Channel " 
-         << normint << channel_element->GetAttributeValue("name") << reset << endl;
+    if (gdata().debug_lvl > 0)
+      cout << endl << gdata().highint << gdata().fgblue << "    Channel " 
+         << gdata().normint << channel_element->GetAttributeValue("name") << gdata().reset << endl;
   
     Element* component_element = channel_element->GetElement();
     while (component_element) {
@@ -585,8 +585,8 @@ bool FGFCS::Load(Element* document)
           cerr << "Unknown FCS component: " << component_element->GetName() << endl;
         }
       } catch(string& s) {
-        cerr << highint << fgred << endl << "  " << s << endl;
-        cerr << reset << endl;
+        cerr << gdata().highint << gdata().fgred << endl << "  " << s << endl;
+        cerr << gdata().reset << endl;
         return false;
       }
       component_element = channel_element->GetNextElement();
@@ -804,6 +804,7 @@ void FGFCS::bindThrottle(unsigned int num)
 
 void FGFCS::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGGasCell.cpp b/src/models/FGGasCell.cpp
index ad16e1d038..2a1fea0b29 100644
--- a/src/models/FGGasCell.cpp
+++ b/src/models/FGGasCell.cpp
@@ -444,6 +444,7 @@ void FGGasCell::Calculate(double dt)
 
 void FGGasCell::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
@@ -498,7 +499,7 @@ const double FGBallonet::Cv_air = 5.0/2.0;        // [??]
 
 FGBallonet::FGBallonet(FGFDMExec* exec, Element* el, unsigned int num,
                        FGGasCell* parent, const struct FGGasCell::Inputs& input)
-  : in(input)
+  : FGJSBBase(exec->gdata()), in(input)
 {
   string token;
   Element* element;
@@ -794,6 +795,7 @@ void FGBallonet::Calculate(double dt)
 
 void FGBallonet::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGGroundReactions.cpp b/src/models/FGGroundReactions.cpp
index 7b6503411d..23c53e2f9b 100644
--- a/src/models/FGGroundReactions.cpp
+++ b/src/models/FGGroundReactions.cpp
@@ -52,7 +52,8 @@ CLASS IMPLEMENTATION
 FGGroundReactions::FGGroundReactions(FGFDMExec* fgex) :
    FGModel(fgex),
    FGSurface(fgex),
-   DsCmd(0.0)
+   DsCmd(0.0),
+   in(fgex->gdata())
 {
   Name = "FGGroundReactions";
 
@@ -288,6 +289,7 @@ void FGGroundReactions::bind(void)
 
 void FGGroundReactions::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGInertial.cpp b/src/models/FGInertial.cpp
index c1c6249866..60cb0ce3b1 100644
--- a/src/models/FGInertial.cpp
+++ b/src/models/FGInertial.cpp
@@ -37,6 +37,7 @@ INCLUDES
 
 #include "FGInertial.h"
 #include "input_output/FGXMLElement.h"
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -49,6 +50,7 @@ CLASS IMPLEMENTATION
 
 FGInertial::FGInertial(FGFDMExec* fgex)
   : FGModel(fgex)
+  , in(fgex->gdata())
 {
   Name = "Earth";
 
@@ -216,7 +218,7 @@ FGColumnVector3 FGInertial::GetGravityJ2(const FGLocation& position) const
 void FGInertial::SetAltitudeAGL(FGLocation& location, double altitudeAGL)
 {
   FGColumnVector3 vDummy;
-  FGLocation contact;
+  FGLocation contact(location.gdata());
   contact.SetEllipse(a, b);
   GroundCallback->GetAGLevel(location, contact, vDummy, vDummy, vDummy);
   double groundHeight = contact.GetGeodAltitude();
@@ -276,6 +278,7 @@ void FGInertial::bind(void)
 
 void FGInertial::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl; 
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGInertial.h b/src/models/FGInertial.h
index c8ab6ff4cc..c6592b7707 100644
--- a/src/models/FGInertial.h
+++ b/src/models/FGInertial.h
@@ -112,7 +112,7 @@ class JSBSIM_API FGInertial : public FGModel {
       @param location Location at which the AGL is evaluated.
       @see SetGroundCallback */
   double GetAltitudeAGL(const FGLocation& location) const {
-    FGLocation lDummy;
+    FGLocation lDummy(const_cast<CommonData&>(location.gdata()));
     FGColumnVector3 vDummy;
     return GroundCallback->GetAGLevel(location, lDummy, vDummy, vDummy,
                                       vDummy);
@@ -195,6 +195,7 @@ class JSBSIM_API FGInertial : public FGModel {
   { return GetTl2ec(location).Transposed(); }
 
   struct Inputs {
+    Inputs(CommonData& c) : Position(c) {}
     FGLocation Position;
   } in;
 
diff --git a/src/models/FGInput.cpp b/src/models/FGInput.cpp
index 1fe66c76e0..c030fee740 100644
--- a/src/models/FGInput.cpp
+++ b/src/models/FGInput.cpp
@@ -91,7 +91,7 @@ bool FGInput::Load(Element* el)
   string type = element->GetAttributeValue("type");
   FGInputType* Input = 0;
 
-  if (debug_lvl > 0) cout << endl << "  Input data set: " << idx << "  " << endl;
+  if (gdata().debug_lvl > 0) cout << endl << "  Input data set: " << idx << "  " << endl;
 
   type = to_upper(type);
 
@@ -220,6 +220,7 @@ void FGInput::Debug(int from)
 {
   string scratch="";
 
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGLGear.cpp b/src/models/FGLGear.cpp
index 049b246a67..0bbb2a6e61 100644
--- a/src/models/FGLGear.cpp
+++ b/src/models/FGLGear.cpp
@@ -170,7 +170,7 @@ FGLGear::FGLGear(Element* el, FGFDMExec* fdmex, int number, const struct Inputs&
   while (force_table) {
     string force_type = force_table->GetAttributeValue("name");
     if (force_type == "CORNERING_COEFF") {
-      ForceY_Table = new FGTable(PropertyManager, force_table);
+      ForceY_Table = new FGTable(gdata(), PropertyManager, force_table);
       break;
     } else {
       cerr << "Undefined force table for " << name << " contact point" << endl;
@@ -190,7 +190,7 @@ FGLGear::FGLGear(Element* el, FGFDMExec* fdmex, int number, const struct Inputs&
 
   element = el->FindElement("orientation");
   if (element && (eContactType == ctBOGEY)) {
-    FGQuaternion quatFromEuler(element->FindElementTripletConvertTo("RAD"));
+    FGQuaternion quatFromEuler(gdata(), element->FindElementTripletConvertTo("RAD"));
 
     mTGear = quatFromEuler.GetT();
   }
@@ -286,7 +286,7 @@ const FGColumnVector3& FGLGear::GetBodyForces(FGSurface *surface)
 
   if (gearPos > 0.99) { // Gear DOWN
     FGColumnVector3 normal, terrainVel, dummy;
-    FGLocation gearLoc, contact;
+    FGLocation gearLoc(gdata()), contact(gdata());
     FGColumnVector3 vWhlBodyVec = Ts2b * (vXYZn - in.vXYZcg);
 
     vLocalGear = in.Tb2l * vWhlBodyVec; // Get local frame wheel location
@@ -524,6 +524,7 @@ void FGLGear::ReportTakeoffOrLanding(void)
     if (WOW) TakeoffDistanceTraveled += in.Vground * in.TotalDeltaT;
   }
 
+  auto debug_lvl = gdata().debug_lvl;
   if ( ReportEnable
        && in.Vground <= 0.05
        && !LandingReported
@@ -906,6 +907,7 @@ void FGLGear::Debug(int from)
   static const char* sBrakeGroup[] = {"NONE", "LEFT", "RIGHT", "CENTER", "NOSE", "TAIL"};
   static const char* sContactType[] = {"BOGEY", "STRUCTURE" };
 
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGLGear.h b/src/models/FGLGear.h
index daf939cee2..eeb41be046 100644
--- a/src/models/FGLGear.h
+++ b/src/models/FGLGear.h
@@ -191,6 +191,7 @@ class JSBSIM_API FGLGear : protected FGSurface, public FGForce
 {
 public:
   struct Inputs {
+    Inputs(CommonData& c) : Location(c) {}
     double Vground;
     double VcalibratedKts;
     double Temperature;
diff --git a/src/models/FGMassBalance.cpp b/src/models/FGMassBalance.cpp
index b65a8e85b7..ad6166e763 100644
--- a/src/models/FGMassBalance.cpp
+++ b/src/models/FGMassBalance.cpp
@@ -451,14 +451,14 @@ void FGMassBalance::PointMass::bind(FGPropertyManager* PropertyManager,
 
 void FGMassBalance::GetMassPropertiesReport(int i)
 {
-  cout << endl << fgblue << highint
+  cout << endl << gdata().fgblue << gdata().highint
        << "  Mass Properties Report (English units: lbf, in, slug-ft^2)"
-       << reset << endl;
-  cout << "                                  " << underon << "    Weight    CG-X    CG-Y"
+       << gdata().reset << endl;
+  cout << "                                  " << gdata().underon << "    Weight    CG-X    CG-Y"
        << "    CG-Z         Ixx         Iyy         Izz"
-       << "         Ixy         Ixz         Iyz" << underoff << endl;
+       << "         Ixy         Ixz         Iyz" << gdata().underoff << endl;
   cout.precision(1);
-  cout << highint << setw(34) << left << "    Base Vehicle " << normint
+  cout << gdata().highint << setw(34) << left << "    Base Vehicle " << gdata().normint
        << right << setw(10) << EmptyWeight
        << setw(8) << vbaseXYZcg(eX) << setw(8) << vbaseXYZcg(eY) << setw(8) << vbaseXYZcg(eZ)
        << setw(12) << baseJ(1,1) << setw(12) << baseJ(2,2) << setw(12) << baseJ(3,3)
@@ -467,7 +467,7 @@ void FGMassBalance::GetMassPropertiesReport(int i)
   for (unsigned int i=0;i<PointMasses.size();i++) {
     PointMass* pm = PointMasses[i];
     double pmweight = pm->GetPointMassWeight();
-    cout << highint << left << setw(4) << i << setw(30) << pm->GetName() << normint
+    cout << gdata().highint << left << setw(4) << i << setw(30) << pm->GetName() << gdata().normint
          << right << setw(10) << pmweight << setw(8) << pm->GetLocation()(eX)
          << setw(8) << pm->GetLocation()(eY) << setw(8) << pm->GetLocation()(eZ)
          << setw(12) << pm->GetPointMassMoI(1,1) << setw(12) << pm->GetPointMassMoI(2,2) << setw(12) << pm->GetPointMassMoI(3,3)
@@ -476,8 +476,8 @@ void FGMassBalance::GetMassPropertiesReport(int i)
 
   cout << FDMExec->GetPropulsionTankReport();
 
-  cout << "    " << underon << setw(136) << " " << underoff << endl;
-  cout << highint << left << setw(30) << "    Total: " << right << setw(14) << Weight
+  cout << "    " << gdata().underon << setw(136) << " " << gdata().underoff << endl;
+  cout << gdata().highint << left << setw(30) << "    Total: " << right << setw(14) << Weight
        << setw(8) << vXYZcg(eX)
        << setw(8) << vXYZcg(eY)
        << setw(8) << vXYZcg(eZ)
@@ -487,7 +487,7 @@ void FGMassBalance::GetMassPropertiesReport(int i)
        << setw(12) << mJ(1,2)
        << setw(12) << mJ(1,3)
        << setw(12) << mJ(2,3)
-       << normint << endl;
+       << gdata().normint << endl;
 
   cout.setf(ios_base::fixed);
 }
@@ -513,6 +513,7 @@ void FGMassBalance::GetMassPropertiesReport(int i)
 
 void FGMassBalance::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGModel.cpp b/src/models/FGModel.cpp
index 5759d72513..c32a57ebe3 100644
--- a/src/models/FGModel.cpp
+++ b/src/models/FGModel.cpp
@@ -54,7 +54,7 @@ GLOBAL DECLARATIONS
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGModel::FGModel(FGFDMExec* fdmex)
+FGModel::FGModel(FGFDMExec* fdmex) : FGModelFunctions(fdmex->gdata())
 {
   FDMExec     = fdmex;
 
@@ -66,14 +66,14 @@ FGModel::FGModel(FGFDMExec* fdmex)
   exe_ctr     = 1;
   rate        = 1;
 
-  if (debug_lvl & 2) cout << "              FGModel Base Class" << endl;
+  if (gdata().debug_lvl & 2) cout << "              FGModel Base Class" << endl;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGModel::~FGModel()
 {
-  if (debug_lvl & 2) cout << "Destroyed:    FGModel" << endl;
+  if (gdata().debug_lvl & 2) cout << "Destroyed:    FGModel" << endl;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -88,7 +88,7 @@ bool FGModel::InitModel(void)
 
 bool FGModel::Run(bool Holding)
 {
-  if (debug_lvl & 4) cout << "Entering Run() for model " << Name << endl;
+  if (gdata().debug_lvl & 4) cout << "Entering Run() for model " << Name << endl;
 
   if (rate == 1) return false; // Fast exit if nothing to do
 
@@ -169,6 +169,7 @@ bool FGModel::Upload(Element* el, bool preLoad)
 
 void FGModel::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGOutput.cpp b/src/models/FGOutput.cpp
index f98abb5a68..71296b7bb3 100644
--- a/src/models/FGOutput.cpp
+++ b/src/models/FGOutput.cpp
@@ -195,7 +195,7 @@ bool FGOutput::Load(int subSystems, std::string protocol, std::string type,
   size_t idx = OutputTypes.size();
   FGOutputType* Output = 0;
 
-  if (debug_lvl > 0) cout << endl << "  Output data set: " << idx << endl;
+  if (gdata().debug_lvl > 0) cout << endl << "  Output data set: " << idx << endl;
 
   type = to_upper(type);
 
@@ -248,7 +248,7 @@ bool FGOutput::Load(Element* document, const SGPath& dir)
   string type = document->GetAttributeValue("type");
   FGOutputType* Output = 0;
 
-  if (debug_lvl > 0) cout << endl << "  Output data set: " << idx << "  " << endl;
+  if (gdata().debug_lvl > 0) cout << endl << "  Output data set: " << idx << "  " << endl;
 
   type = to_upper(type);
 
@@ -313,6 +313,7 @@ SGPath FGOutput::FindFullPathName(const SGPath& path) const
 
 void FGOutput::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/FGPropagate.cpp b/src/models/FGPropagate.cpp
index 5dc0f127b9..b4032b0fc2 100644
--- a/src/models/FGPropagate.cpp
+++ b/src/models/FGPropagate.cpp
@@ -81,6 +81,8 @@ CLASS IMPLEMENTATION
 
 FGPropagate::FGPropagate(FGFDMExec* fdmex)
   : FGModel(fdmex)
+  , VState(fdmex->gdata())
+  , Qec2b(fdmex->gdata())
 {
   Debug(0);
   Name = "FGPropagate";
@@ -98,7 +100,7 @@ FGPropagate::FGPropagate(FGFDMExec* fdmex)
   VState.dqPQRidot.resize(5, FGColumnVector3(0.0,0.0,0.0));
   VState.dqUVWidot.resize(5, FGColumnVector3(0.0,0.0,0.0));
   VState.dqInertialVelocity.resize(5, FGColumnVector3(0.0,0.0,0.0));
-  VState.dqQtrndot.resize(5, FGQuaternion(0.0,0.0,0.0));
+  VState.dqQtrndot.resize(5, FGQuaternion(gdata(), 0.0, 0.0, 0.0));
 
   epa = 0.0;
 
@@ -126,7 +128,7 @@ bool FGPropagate::InitModel(void)
   VState.dqPQRidot.resize(5, FGColumnVector3(0.0,0.0,0.0));
   VState.dqUVWidot.resize(5, FGColumnVector3(0.0,0.0,0.0));
   VState.dqInertialVelocity.resize(5, FGColumnVector3(0.0,0.0,0.0));
-  VState.dqQtrndot.resize(5, FGColumnVector3(0.0,0.0,0.0));
+  VState.dqQtrndot.resize(5, FGQuaternion(gdata(), FGColumnVector3(0.0, 0.0, 0.0)));
 
   integrator_rotational_rate = eRectEuler;
   integrator_translational_rate = eAdamsBashforth2;
@@ -162,7 +164,7 @@ void FGPropagate::SetInitialState(const FGInitialCondition *FGIC)
   // frame relative to the local frame.
   VState.qAttitudeLocal = FGIC->GetOrientation();
 
-  VState.qAttitudeECI = Ti2l.GetQuaternion()*VState.qAttitudeLocal;
+  VState.qAttitudeECI = Ti2l.GetQuaternion(gdata()) * VState.qAttitudeLocal;
   UpdateBodyMatrices();
 
   // Set the velocities in the instantaneus body frame
@@ -269,7 +271,7 @@ bool FGPropagate::Run(bool Holding)
   // Angular orientation derivative
   CalculateQuatdot();
 
-  VState.qAttitudeLocal = Tl2b.GetQuaternion();
+  VState.qAttitudeLocal = Tl2b.GetQuaternion(gdata());
 
   // Compute vehicle velocity wrt ECEF frame, expressed in Local horizontal
   // frame.
@@ -393,7 +395,7 @@ void FGPropagate::Integrate( FGQuaternion& Integrand,
       // The formula from Buss' paper is transposed below to quaternions and is
       // actually the exact solution of the quaternion differential equation
       // qdot = 1/2*w*q when w is constant.
-      Integrand = Integrand * QExp(0.5 * dt * VState.vPQRi);
+      Integrand = Integrand * QExp(gdata(), 0.5 * dt * VState.vPQRi);
     }
     return; // No need to normalize since the quaternion exponential is always normal
   case eBuss2:
@@ -404,7 +406,7 @@ void FGPropagate::Integrate( FGQuaternion& Integrand,
       FGColumnVector3 wi = VState.vPQRi;
       FGColumnVector3 wdoti = in.vPQRidot;
       FGColumnVector3 omega = wi + 0.5*dt*wdoti + dt*dt/12.*wdoti*wi;
-      Integrand = Integrand * QExp(0.5 * dt * omega);
+      Integrand = Integrand * QExp(gdata(), 0.5 * dt * omega);
     }
     return; // No need to normalize since the quaternion exponential is always normal
   case eLocalLinearization:
@@ -423,7 +425,7 @@ void FGPropagate::Integrate( FGQuaternion& Integrand,
       double C3 = 4.0 * (1.0 - C1) / (omegak*omegak);
       double C4 = 4.0 * (dt - C2) / (omegak*omegak);
       FGColumnVector3 Omega = C2*wi + C3*wdoti + C4*wi*wdoti;
-      FGQuaternion q;
+      FGQuaternion q(gdata());
 
       q(1) = C1 - C4*DotProduct(wi, wdoti);
       q(2) = Omega(eP);
@@ -488,7 +490,7 @@ void FGPropagate::UpdateBodyMatrices(void)
   Tec2b = Ti2b * Tec2i;               // ECEF to body frame transform
   Tb2ec = Tec2b.Transposed();         // body to ECEF frame tranform
 
-  Qec2b = Tec2b.GetQuaternion();
+  Qec2b = Tec2b.GetQuaternion(gdata());
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -498,7 +500,7 @@ void FGPropagate::SetInertialOrientation(const FGQuaternion& Qi)
   VState.qAttitudeECI = Qi;
   VState.qAttitudeECI.Normalize();
   UpdateBodyMatrices();
-  VState.qAttitudeLocal = Tl2b.GetQuaternion();
+  VState.qAttitudeLocal = Tl2b.GetQuaternion(gdata());
   CalculateQuatdot();
 }
 
@@ -538,7 +540,7 @@ void FGPropagate::SetAltitudeASL(double altASL)
 
 void FGPropagate::RecomputeLocalTerrainVelocity()
 {
-  FGLocation contact;
+  FGLocation contact(gdata());
   FGColumnVector3 normal;
   Inertial->GetContactPoint(VState.vLocation, contact, normal,
                             LocalTerrainVelocity, LocalTerrainAngularVelocity);
@@ -549,7 +551,7 @@ void FGPropagate::RecomputeLocalTerrainVelocity()
 double FGPropagate::GetTerrainElevation(void) const
 {
   FGColumnVector3 vDummy;
-  FGLocation contact;
+  FGLocation contact(const_cast<CommonData&>(gdata()));
   contact.SetEllipse(in.SemiMajor, in.SemiMinor);
   Inertial->GetContactPoint(VState.vLocation, contact, vDummy, vDummy, vDummy);
   return contact.GetGeodAltitude();
@@ -566,7 +568,7 @@ void FGPropagate::SetTerrainElevation(double terrainElev)
 
 double FGPropagate::GetLocalTerrainRadius(void) const
 {
-  FGLocation contact;
+  FGLocation contact(const_cast<CommonData&>(gdata()));
   FGColumnVector3 vDummy;
   Inertial->GetContactPoint(VState.vLocation, contact, vDummy, vDummy, vDummy);
   return contact.GetRadius();
@@ -627,7 +629,7 @@ void FGPropagate::UpdateVehicleState(void)
   UpdateLocationMatrices();
   UpdateBodyMatrices();
   vVel = Tb2l * VState.vUVW;
-  VState.qAttitudeLocal = Tl2b.GetQuaternion();
+  VState.qAttitudeLocal = Tl2b.GetQuaternion(gdata());
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -650,32 +652,32 @@ FGColumnVector3 FGPropagate::GetEulerDeg(void) const
 void FGPropagate::DumpState(void)
 {
   cout << endl;
-  cout << fgblue
-       << "------------------------------------------------------------------" << reset << endl;
-  cout << highint
-       << "State Report at sim time: " << FDMExec->GetSimTime() << " seconds" << reset << endl;
-  cout << "  " << underon
-       <<   "Position" << underoff << endl;
+  cout << gdata().fgblue
+       << "------------------------------------------------------------------" << gdata().reset << endl;
+  cout << gdata().highint
+       << "State Report at sim time: " << FDMExec->GetSimTime() << " seconds" << gdata().reset << endl;
+  cout << "  " << gdata().underon
+       <<   "Position" << gdata().underoff << endl;
   cout << "    ECI:   " << VState.vInertialPosition.Dump(", ") << " (x,y,z, in ft)" << endl;
   cout << "    ECEF:  " << VState.vLocation << " (x,y,z, in ft)"  << endl;
   cout << "    Local: " << VState.vLocation.GetGeodLatitudeDeg()
                         << ", " << VState.vLocation.GetLongitudeDeg()
                         << ", " << GetAltitudeASL() << " (geodetic lat, lon, alt ASL in deg and ft)" << endl;
 
-  cout << endl << "  " << underon
-       <<   "Orientation" << underoff << endl;
+  cout << endl << "  " << gdata().underon
+       <<   "Orientation" << gdata().underoff << endl;
   cout << "    ECI:   " << VState.qAttitudeECI.GetEulerDeg().Dump(", ") << " (phi, theta, psi in deg)" << endl;
   cout << "    Local: " << VState.qAttitudeLocal.GetEulerDeg().Dump(", ") << " (phi, theta, psi in deg)" << endl;
 
-  cout << endl << "  " << underon
-       <<   "Velocity" << underoff << endl;
+  cout << endl << "  " << gdata().underon
+       <<   "Velocity" << gdata().underoff << endl;
   cout << "    ECI:   " << VState.vInertialVelocity.Dump(", ") << " (x,y,z in ft/s)" << endl;
   cout << "    ECEF:  " << (Tb2ec * VState.vUVW).Dump(", ")  << " (x,y,z in ft/s)"  << endl;
   cout << "    Local: " << GetVel() << " (n,e,d in ft/sec)" << endl;
   cout << "    Body:  " << GetUVW() << " (u,v,w in ft/sec)" << endl;
 
-  cout << endl << "  " << underon
-       <<   "Body Rates (relative to given frame, expressed in body frame)" << underoff << endl;
+  cout << endl << "  " << gdata().underon
+       <<   "Body Rates (relative to given frame, expressed in body frame)" << gdata().underoff << endl;
   cout << "    ECI:   " << (VState.vPQRi*radtodeg).Dump(", ") << " (p,q,r in deg/s)" << endl;
   cout << "    ECEF:  " << (VState.vPQR*radtodeg).Dump(", ") << " (p,q,r in deg/s)" << endl;
 }
@@ -861,6 +863,7 @@ void FGPropagate::bind(void)
 
 void FGPropagate::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
@@ -875,92 +878,92 @@ void FGPropagate::Debug(int from)
   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
   }
   if (debug_lvl & 8 && from == 2) { // Runtime state variables
-    cout << endl << fgblue << highint << left
+    cout << endl << gdata().fgblue << gdata().highint << left
          << "  Propagation Report (English units: ft, degrees) at simulation time " << FDMExec->GetSimTime() << " seconds"
-         << reset << endl;
+         << gdata().reset << endl;
     cout << endl;
-    cout << highint << "  Earth Position Angle (deg): " << setw(8) << setprecision(3) << reset
+    cout << gdata().highint << "  Earth Position Angle (deg): " << setw(8) << setprecision(3) << gdata().reset
          << GetEarthPositionAngleDeg() << endl;
     cout << endl;
-    cout << highint << "  Body velocity (ft/sec): " << setw(8) << setprecision(3) << reset << VState.vUVW << endl;
-    cout << highint << "  Local velocity (ft/sec): " << setw(8) << setprecision(3) << reset << vVel << endl;
-    cout << highint << "  Inertial velocity (ft/sec): " << setw(8) << setprecision(3) << reset << VState.vInertialVelocity << endl;
-    cout << highint << "  Inertial Position (ft): " << setw(10) << setprecision(3) << reset << VState.vInertialPosition << endl;
-    cout << highint << "  Latitude (deg): " << setw(8) << setprecision(3) << reset << VState.vLocation.GetLatitudeDeg() << endl;
-    cout << highint << "  Longitude (deg): " << setw(8) << setprecision(3) << reset << VState.vLocation.GetLongitudeDeg() << endl;
-    cout << highint << "  Altitude ASL (ft): " << setw(8) << setprecision(3) << reset << GetAltitudeASL() << endl;
-//    cout << highint << "  Acceleration (NED, ft/sec^2): " << setw(8) << setprecision(3) << reset << Tb2l*GetUVWdot() << endl;
+    cout << gdata().highint << "  Body velocity (ft/sec): " << setw(8) << setprecision(3) << gdata().reset << VState.vUVW << endl;
+    cout << gdata().highint << "  Local velocity (ft/sec): " << setw(8) << setprecision(3) << gdata().reset << vVel << endl;
+    cout << gdata().highint << "  Inertial velocity (ft/sec): " << setw(8) << setprecision(3) << gdata().reset << VState.vInertialVelocity << endl;
+    cout << gdata().highint << "  Inertial Position (ft): " << setw(10) << setprecision(3) << gdata().reset << VState.vInertialPosition << endl;
+    cout << gdata().highint << "  Latitude (deg): " << setw(8) << setprecision(3) << gdata().reset << VState.vLocation.GetLatitudeDeg() << endl;
+    cout << gdata().highint << "  Longitude (deg): " << setw(8) << setprecision(3) << gdata().reset << VState.vLocation.GetLongitudeDeg() << endl;
+    cout << gdata().highint << "  Altitude ASL (ft): " << setw(8) << setprecision(3) << gdata().reset << GetAltitudeASL() << endl;
+//    cout << gdata().highint << "  Acceleration (NED, ft/sec^2): " << setw(8) << setprecision(3) << gdata().reset << Tb2l*GetUVWdot() << endl;
     cout << endl;
-    cout << highint << "  Matrix ECEF to Body (Orientation of Body with respect to ECEF): "
-                    << reset << endl << Tec2b.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tec2b.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix ECEF to Body (Orientation of Body with respect to ECEF): "
+                    << gdata().reset << endl << Tec2b.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tec2b.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Body to ECEF (Orientation of ECEF with respect to Body):"
-                    << reset << endl << Tb2ec.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tb2ec.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Body to ECEF (Orientation of ECEF with respect to Body):"
+                    << gdata().reset << endl << Tb2ec.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tb2ec.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Local to Body (Orientation of Body with respect to Local):"
-                    << reset << endl << Tl2b.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tl2b.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Local to Body (Orientation of Body with respect to Local):"
+                    << gdata().reset << endl << Tl2b.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tl2b.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Body to Local (Orientation of Local with respect to Body):"
-                    << reset << endl << Tb2l.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tb2l.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Body to Local (Orientation of Local with respect to Body):"
+                    << gdata().reset << endl << Tb2l.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tb2l.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Local to ECEF (Orientation of ECEF with respect to Local):"
-                    << reset << endl << Tl2ec.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tl2ec.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Local to ECEF (Orientation of ECEF with respect to Local):"
+                    << gdata().reset << endl << Tl2ec.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tl2ec.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix ECEF to Local (Orientation of Local with respect to ECEF):"
-                    << reset << endl << Tec2l.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tec2l.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix ECEF to Local (Orientation of Local with respect to ECEF):"
+                    << gdata().reset << endl << Tec2l.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tec2l.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix ECEF to Inertial (Orientation of Inertial with respect to ECEF):"
-                    << reset << endl << Tec2i.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tec2i.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix ECEF to Inertial (Orientation of Inertial with respect to ECEF):"
+                    << gdata().reset << endl << Tec2i.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tec2i.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Inertial to ECEF (Orientation of ECEF with respect to Inertial):"
-                    << reset << endl << Ti2ec.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Ti2ec.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Inertial to ECEF (Orientation of ECEF with respect to Inertial):"
+                    << gdata().reset << endl << Ti2ec.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Ti2ec.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Inertial to Body (Orientation of Body with respect to Inertial):"
-                    << reset << endl << Ti2b.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Ti2b.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Inertial to Body (Orientation of Body with respect to Inertial):"
+                    << gdata().reset << endl << Ti2b.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Ti2b.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Body to Inertial (Orientation of Inertial with respect to Body):"
-                    << reset << endl << Tb2i.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tb2i.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Body to Inertial (Orientation of Inertial with respect to Body):"
+                    << gdata().reset << endl << Tb2i.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tb2i.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Inertial to Local (Orientation of Local with respect to Inertial):"
-                    << reset << endl << Ti2l.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Ti2l.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Inertial to Local (Orientation of Local with respect to Inertial):"
+                    << gdata().reset << endl << Ti2l.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Ti2l.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
-    cout << highint << "  Matrix Local to Inertial (Orientation of Inertial with respect to Local):"
-                    << reset << endl << Tl2i.Dump("\t", "    ") << endl;
-    cout << highint << "    Associated Euler angles (deg): " << setw(8)
-                    << setprecision(3) << reset << (Tl2i.GetQuaternion().GetEuler()*radtodeg)
+    cout << gdata().highint << "  Matrix Local to Inertial (Orientation of Inertial with respect to Local):"
+                    << gdata().reset << endl << Tl2i.Dump("\t", "    ") << endl;
+    cout << gdata().highint << "    Associated Euler angles (deg): " << setw(8)
+                    << setprecision(3) << gdata().reset << (Tl2i.GetQuaternion(gdata()).GetEuler()*radtodeg)
                     << endl << endl;
 
     cout << setprecision(6); // reset the output stream
diff --git a/src/models/FGPropagate.h b/src/models/FGPropagate.h
index 293b24b656..7ce1106fa9 100644
--- a/src/models/FGPropagate.h
+++ b/src/models/FGPropagate.h
@@ -96,6 +96,7 @@ class JSBSIM_API FGPropagate : public FGModel {
   /** The current vehicle state vector structure contains the translational and
     angular position, and the translational and angular velocity. */
   struct VehicleState {
+    VehicleState(CommonData& c) : vLocation(c), qAttitudeLocal(c), qAttitudeECI(c), vQtrndot(c) {}
     /** Represents the current location of the vehicle in Earth centered Earth
         fixed (ECEF) frame.
         units ft */
@@ -583,18 +584,18 @@ class JSBSIM_API FGPropagate : public FGModel {
   void SetLocation(const FGLocation& l);
   void SetLocation(const FGColumnVector3& lv)
   {
-      FGLocation l = FGLocation(lv);
+      FGLocation l = FGLocation(gdata(), lv);
       SetLocation(l);
   }
   void SetPosition(const double Lon, const double Lat, const double Radius)
   {
-      FGLocation l = FGLocation(Lon, Lat, Radius);
+      FGLocation l = FGLocation(gdata(), Lon, Lat, Radius);
       SetLocation(l);
   }
 
   void NudgeBodyLocation(const FGColumnVector3& deltaLoc) {
     VState.vInertialPosition -= Tb2i*deltaLoc;
-    VState.vLocation -= Tb2ec*deltaLoc;
+    VState.vLocation -= FGLocation(VState.vLocation.gdata(), Tb2ec*deltaLoc);
   }
 
   /** Sets the property forces/hold-down. This allows to do hard 'hold-down'
diff --git a/src/models/FGPropulsion.cpp b/src/models/FGPropulsion.cpp
index 685498b0a1..f54598d27d 100644
--- a/src/models/FGPropulsion.cpp
+++ b/src/models/FGPropulsion.cpp
@@ -61,8 +61,6 @@ using namespace std;
 
 namespace JSBSim {
 
-extern short debug_lvl;
-
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
@@ -426,7 +424,7 @@ bool FGPropulsion::Load(Element* el)
         return false;
       }
     } catch (std::string& str) {
-      cerr << endl << fgred << str << reset << endl;
+      cerr << endl << gdata().fgred << str << gdata().reset << endl;
       return false;
     }
 
@@ -542,7 +540,7 @@ string FGPropulsion::GetPropulsionTankReport()
     } else {
       tankname = "(Unknown tank type)";
     }
-    outstream << highint << left << setw(4) << i << setw(30) << tankname << normint
+    outstream << gdata().highint << left << setw(4) << i << setw(30) << tankname << gdata().normint
       << right << setw(10) << tank->GetContents() << setw(8) << tank->GetXYZ(eX)
          << setw(8) << tank->GetXYZ(eY) << setw(8) << tank->GetXYZ(eZ)
          << setw(12) << tank->GetIxx() << setw(12) << tank->GetIyy()
@@ -852,6 +850,7 @@ void FGPropulsion::bind(void)
 
 void FGPropulsion::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/atmosphere/FGMSIS.cpp b/src/models/atmosphere/FGMSIS.cpp
index 41be26913d..08810c7227 100644
--- a/src/models/atmosphere/FGMSIS.cpp
+++ b/src/models/atmosphere/FGMSIS.cpp
@@ -1604,6 +1604,7 @@ void MSIS::gts7(struct nrlmsise_input *input, struct nrlmsise_flags *flags,
 
 void MSIS::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/atmosphere/FGMars.cpp b/src/models/atmosphere/FGMars.cpp
index 6362f70ce0..aca5a5ea93 100644
--- a/src/models/atmosphere/FGMars.cpp
+++ b/src/models/atmosphere/FGMars.cpp
@@ -43,6 +43,7 @@ INCLUDES
 
 #include "FGMars.h"
 #include <iostream>
+#include "FGFDMExec.h"
 
 using namespace std;
 
@@ -102,6 +103,7 @@ void FGMars::Calculate(double altitude)
 
 void FGMars::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/atmosphere/FGStandardAtmosphere.cpp b/src/models/atmosphere/FGStandardAtmosphere.cpp
index 1077c52c65..66e8f7ab20 100644
--- a/src/models/atmosphere/FGStandardAtmosphere.cpp
+++ b/src/models/atmosphere/FGStandardAtmosphere.cpp
@@ -59,8 +59,8 @@ CLASS IMPLEMENTATION
 FGStandardAtmosphere::FGStandardAtmosphere(FGFDMExec* fdmex)
   : FGAtmosphere(fdmex), StdSLpressure(StdDaySLpressure), TemperatureBias(0.0),
     TemperatureDeltaGradient(0.0), VaporMassFraction(0.0),
-    SaturatedVaporPressure(0.0), StdAtmosTemperatureTable(9),
-    MaxVaporMassFraction(10)
+    SaturatedVaporPressure(0.0), StdAtmosTemperatureTable(fdmex->gdata(), 9),
+    MaxVaporMassFraction(fdmex->gdata(), 10)
 {
   Name = "FGStandardAtmosphere";
 
@@ -718,6 +718,7 @@ void FGStandardAtmosphere::bind(void)
 
 void FGStandardAtmosphere::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/atmosphere/FGWinds.cpp b/src/models/atmosphere/FGWinds.cpp
index 550281977e..736dddb84f 100644
--- a/src/models/atmosphere/FGWinds.cpp
+++ b/src/models/atmosphere/FGWinds.cpp
@@ -91,7 +91,7 @@ FGWinds::FGWinds(FGFDMExec* fdmex) : FGModel(fdmex)
   // Milspec turbulence model
   windspeed_at_20ft = 0.;
   probability_of_exceedence_index = 0;
-  POE_Table = new FGTable(7,12);
+  POE_Table = new FGTable(gdata(), 7, 12);
   // this is Figure 7 from p. 49 of MIL-F-8785C
   // rows: probability of exceedance curve index, cols: altitude in ft
   *POE_Table
@@ -586,6 +586,7 @@ void FGWinds::bind(void)
 
 void FGWinds::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGAccelerometer.cpp b/src/models/flight_control/FGAccelerometer.cpp
index 6d7962815e..a142b7b335 100644
--- a/src/models/flight_control/FGAccelerometer.cpp
+++ b/src/models/flight_control/FGAccelerometer.cpp
@@ -52,7 +52,7 @@ CLASS IMPLEMENTATION
 
 FGAccelerometer::FGAccelerometer(FGFCS* fcs, Element* element)
   : FGSensor(fcs, element),
-    FGSensorOrientation(element)
+    FGSensorOrientation(fcs->gdata(), element)
 {
   Propagate = fcs->GetExec()->GetPropagate();
   Accelerations = fcs->GetExec()->GetAccelerations();
@@ -127,6 +127,7 @@ void FGAccelerometer::Debug(int from)
 {
   string ax[4] = {"none", "X", "Y", "Z"};
 
+  auto debug_lvl = FGSensorOrientation::gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGActuator.cpp b/src/models/flight_control/FGActuator.cpp
index b0cc9d4cfc..ab0b900cf3 100644
--- a/src/models/flight_control/FGActuator.cpp
+++ b/src/models/flight_control/FGActuator.cpp
@@ -331,6 +331,7 @@ void FGActuator::InitializeLagCoefficients()
 
 void FGActuator::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGAngles.cpp b/src/models/flight_control/FGAngles.cpp
index 7d9dbc35d1..256b5ef375 100644
--- a/src/models/flight_control/FGAngles.cpp
+++ b/src/models/flight_control/FGAngles.cpp
@@ -177,6 +177,7 @@ bool FGAngles::Run(void )
 
 void FGAngles::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGDeadBand.cpp b/src/models/flight_control/FGDeadBand.cpp
index a09e0b1902..bf94e4668f 100644
--- a/src/models/flight_control/FGDeadBand.cpp
+++ b/src/models/flight_control/FGDeadBand.cpp
@@ -121,6 +121,7 @@ bool FGDeadBand::Run(void)
 
 void FGDeadBand::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGDistributor.cpp b/src/models/flight_control/FGDistributor.cpp
index efcfb45e9d..afa4c2dc5f 100644
--- a/src/models/flight_control/FGDistributor.cpp
+++ b/src/models/flight_control/FGDistributor.cpp
@@ -66,7 +66,7 @@ FGDistributor::FGDistributor(FGFCS* fcs, Element* element)
   while (case_element) {
     Case* current_case = new Case;
     Element* test_element = case_element->FindElement("test");
-    if (test_element) current_case->SetTest(new FGCondition(test_element, PropertyManager));
+    if (test_element) current_case->SetTest(new FGCondition(gdata(), test_element, PropertyManager));
     Element* prop_val_element = case_element->FindElement("property");
     while (prop_val_element) {
       string value_string = prop_val_element->GetAttributeValue("value");
@@ -129,6 +129,7 @@ bool FGDistributor::Run(void )
 
 void FGDistributor::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGFCSComponent.cpp b/src/models/flight_control/FGFCSComponent.cpp
index dbfe6cc46e..c07e2088cc 100644
--- a/src/models/flight_control/FGFCSComponent.cpp
+++ b/src/models/flight_control/FGFCSComponent.cpp
@@ -49,7 +49,8 @@ namespace JSBSim {
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGFCSComponent::FGFCSComponent(FGFCS* _fcs, Element* element) : fcs(_fcs)
+FGFCSComponent::FGFCSComponent(FGFCS* _fcs, Element* element)
+  : FGJSBBase(_fcs->gdata()), fcs(_fcs)
 {
   Input = Output = delay_time = 0.0;
   delay = index = 0;
@@ -343,6 +344,7 @@ void FGFCSComponent::bind(Element* el)
 
 void FGFCSComponent::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGFCSFunction.cpp b/src/models/flight_control/FGFCSFunction.cpp
index 23b881701c..6e72c25ae6 100644
--- a/src/models/flight_control/FGFCSFunction.cpp
+++ b/src/models/flight_control/FGFCSFunction.cpp
@@ -114,6 +114,7 @@ bool FGFCSFunction::Run(void )
 
 void FGFCSFunction::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGFilter.cpp b/src/models/flight_control/FGFilter.cpp
index 08681261e8..b08c57fd71 100644
--- a/src/models/flight_control/FGFilter.cpp
+++ b/src/models/flight_control/FGFilter.cpp
@@ -209,6 +209,7 @@ bool FGFilter::Run(void)
 
 void FGFilter::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGGain.cpp b/src/models/flight_control/FGGain.cpp
index ac2d36c20d..b65b706723 100644
--- a/src/models/flight_control/FGGain.cpp
+++ b/src/models/flight_control/FGGain.cpp
@@ -62,7 +62,7 @@ FGGain::FGGain(FGFCS* fcs, Element* element) : FGFCSComponent(fcs, element)
   if (Type == "PURE_GAIN") {
     if ( !element->FindElement("gain") ) {
       cerr << element->ReadFrom()
-           << highint << "      No GAIN specified (default: 1.0)" << normint
+           << gdata().highint << "      No GAIN specified (default: 1.0)" << gdata().normint
            << endl;
     }
   }
@@ -108,7 +108,7 @@ FGGain::FGGain(FGFCS* fcs, Element* element) : FGFCSComponent(fcs, element)
 
   if (Type == "SCHEDULED_GAIN") {
     if (element->FindElement("table")) {
-      Table = new FGTable(PropertyManager, element->FindElement("table"));
+      Table = new FGTable(gdata(), PropertyManager, element->FindElement("table"));
     } else {
       cerr << element->ReadFrom()
            << "A table must be provided for the scheduled gain component"
@@ -190,6 +190,7 @@ bool FGGain::Run(void )
 
 void FGGain::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGGyro.cpp b/src/models/flight_control/FGGyro.cpp
index f144422b52..b8c382bb90 100644
--- a/src/models/flight_control/FGGyro.cpp
+++ b/src/models/flight_control/FGGyro.cpp
@@ -49,7 +49,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGGyro::FGGyro(FGFCS* fcs, Element* element) : FGSensor(fcs, element),
-                                               FGSensorOrientation(element)
+                                               FGSensorOrientation(fcs->gdata(), element)
 {
   Propagate = fcs->GetExec()->GetPropagate();
 
@@ -107,6 +107,7 @@ void FGGyro::Debug(int from)
 {
   string ax[4] = {"none", "X", "Y", "Z"};
 
+  auto debug_lvl = FGSensor::gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGKinemat.cpp b/src/models/flight_control/FGKinemat.cpp
index 039860f656..90d66ecd5c 100644
--- a/src/models/flight_control/FGKinemat.cpp
+++ b/src/models/flight_control/FGKinemat.cpp
@@ -175,6 +175,7 @@ bool FGKinemat::Run(void )
 
 void FGKinemat::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGLinearActuator.cpp b/src/models/flight_control/FGLinearActuator.cpp
index b18ca841a1..2580e7330c 100644
--- a/src/models/flight_control/FGLinearActuator.cpp
+++ b/src/models/flight_control/FGLinearActuator.cpp
@@ -235,6 +235,7 @@ bool FGLinearActuator::Run(void )
 //       a message is printed out when they go out of bounds
 void FGLinearActuator::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGMagnetometer.cpp b/src/models/flight_control/FGMagnetometer.cpp
index 14218bde07..25cbbfb701 100644
--- a/src/models/flight_control/FGMagnetometer.cpp
+++ b/src/models/flight_control/FGMagnetometer.cpp
@@ -52,7 +52,7 @@ CLASS IMPLEMENTATION
 
 
 FGMagnetometer::FGMagnetometer(FGFCS* fcs, Element* element)
-  : FGSensor(fcs, element), FGSensorOrientation(element), counter(0),
+  : FGSensor(fcs, element), FGSensorOrientation(fcs->gdata(), element), counter(0),
     INERTIAL_UPDATE_RATE(1000)
 {
   Propagate = fcs->GetExec()->GetPropagate();
@@ -170,6 +170,7 @@ void FGMagnetometer::Debug(int from)
 {
   string ax[4] = {"none", "X", "Y", "Z"};
 
+  auto debug_lvl = FGSensor::gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGPID.cpp b/src/models/flight_control/FGPID.cpp
index 24de8a4868..fda93a10b7 100644
--- a/src/models/flight_control/FGPID.cpp
+++ b/src/models/flight_control/FGPID.cpp
@@ -230,6 +230,7 @@ bool FGPID::Run(void )
 
 void FGPID::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGSensor.cpp b/src/models/flight_control/FGSensor.cpp
index 5c0d085707..54d00139c2 100644
--- a/src/models/flight_control/FGSensor.cpp
+++ b/src/models/flight_control/FGSensor.cpp
@@ -298,6 +298,7 @@ void FGSensor::bind(Element* el)
 
 void FGSensor::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGSensorOrientation.h b/src/models/flight_control/FGSensorOrientation.h
index 0c62034d05..62066623ae 100644
--- a/src/models/flight_control/FGSensorOrientation.h
+++ b/src/models/flight_control/FGSensorOrientation.h
@@ -69,7 +69,7 @@ CLASS DECLARATION
 class FGSensorOrientation  : public FGJSBBase
 {
 public:
-  FGSensorOrientation(Element* element)
+  FGSensorOrientation(CommonData& c, Element* element) : FGJSBBase(c)
   {
     Element* orient_element = element->FindElement("orientation");
     if (orient_element) vOrient = orient_element->FindElementTripletConvertTo("RAD");
diff --git a/src/models/flight_control/FGSummer.cpp b/src/models/flight_control/FGSummer.cpp
index 978168da57..0e4c43f86a 100644
--- a/src/models/flight_control/FGSummer.cpp
+++ b/src/models/flight_control/FGSummer.cpp
@@ -104,6 +104,7 @@ bool FGSummer::Run(void)
 
 void FGSummer::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGSwitch.cpp b/src/models/flight_control/FGSwitch.cpp
index 926308c796..76d0c5de2b 100644
--- a/src/models/flight_control/FGSwitch.cpp
+++ b/src/models/flight_control/FGSwitch.cpp
@@ -96,7 +96,7 @@ FGSwitch::FGSwitch(FGFCS* fcs, Element* element) : FGFCSComponent(fcs, element)
   test_element = element->FindElement("test");
   while (test_element) {
     current_test = new Test;
-    current_test->condition = new FGCondition(test_element, PropertyManager);
+    current_test->condition = new FGCondition(gdata(), test_element, PropertyManager);
     value = test_element->GetAttributeValue("value");
     current_test->setTestValue(value, Name, PropertyManager);
     tests.push_back(current_test);
@@ -187,6 +187,7 @@ void FGSwitch::VerifyProperties(void)
 
 void FGSwitch::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/flight_control/FGWaypoint.cpp b/src/models/flight_control/FGWaypoint.cpp
index c813c0a4ed..9043918a6a 100644
--- a/src/models/flight_control/FGWaypoint.cpp
+++ b/src/models/flight_control/FGWaypoint.cpp
@@ -55,7 +55,7 @@ CLASS IMPLEMENTATION
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGWaypoint::FGWaypoint(FGFCS* fcs, Element* element)
-  : FGFCSComponent(fcs, element)
+  : FGFCSComponent(fcs, element), source(fcs->gdata())
 {
   if      (Type == "WAYPOINT_HEADING")  WaypointType = eHeading;
   else if (Type == "WAYPOINT_DISTANCE") WaypointType = eDistance;
@@ -242,6 +242,7 @@ bool FGWaypoint::Run(void )
 
 void FGWaypoint::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGElectric.cpp b/src/models/propulsion/FGElectric.cpp
index 06d01a9898..c8c5b619c1 100644
--- a/src/models/propulsion/FGElectric.cpp
+++ b/src/models/propulsion/FGElectric.cpp
@@ -56,7 +56,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGElectric::FGElectric(FGFDMExec* exec, Element *el, int engine_number, struct FGEngine::Inputs& input)
-  : FGEngine(engine_number, input)
+  : FGEngine(exec->gdata(), engine_number, input)
 {
   Load(exec,el);
 
@@ -158,6 +158,7 @@ string FGElectric::GetEngineValues(const string& delimiter)
 
 void FGElectric::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGEngine.cpp b/src/models/propulsion/FGEngine.cpp
index 0241c28377..747052d407 100644
--- a/src/models/propulsion/FGEngine.cpp
+++ b/src/models/propulsion/FGEngine.cpp
@@ -52,8 +52,8 @@ namespace JSBSim {
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGEngine::FGEngine(int engine_number, struct Inputs& input)
-  : in(input), EngineNumber(engine_number)
+FGEngine::FGEngine(CommonData& c, int engine_number, struct Inputs& input)
+  : FGModelFunctions(c), in(input), EngineNumber(engine_number)
 {
   Type = etUnknown;
   SLFuelFlowMax = 0.0;
@@ -262,6 +262,7 @@ bool FGEngine::Load(FGFDMExec *exec, Element *engine_element)
 
 void FGEngine::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGEngine.h b/src/models/propulsion/FGEngine.h
index 5edc751ce2..12dd59ef5f 100644
--- a/src/models/propulsion/FGEngine.h
+++ b/src/models/propulsion/FGEngine.h
@@ -130,7 +130,7 @@ class FGEngine : public FGModelFunctions
     double TotalDeltaT;
   };
 
-  FGEngine(int engine_number, struct Inputs& input);
+  FGEngine(CommonData& c, int engine_number, struct Inputs& input);
   ~FGEngine() override;
 
   enum EngineType {etUnknown, etRocket, etPiston, etTurbine, etTurboprop, etElectric};
diff --git a/src/models/propulsion/FGForce.cpp b/src/models/propulsion/FGForce.cpp
index 30350350bd..d26c757150 100644
--- a/src/models/propulsion/FGForce.cpp
+++ b/src/models/propulsion/FGForce.cpp
@@ -51,7 +51,7 @@ namespace JSBSim {
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGForce::FGForce(FGFDMExec *FDMExec)
-  : fdmex(FDMExec), MassBalance(fdmex->GetMassBalance()), ttype(tNone)
+  : FGJSBBase(FDMExec->gdata()), fdmex(FDMExec), MassBalance(fdmex->GetMassBalance()), ttype(tNone)
 {
   vFn.InitMatrix();
   vMn.InitMatrix();
@@ -176,6 +176,7 @@ void FGForce::SetAnglesToBody(double broll, double bpitch, double byaw)
 
 void FGForce::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGNozzle.cpp b/src/models/propulsion/FGNozzle.cpp
index 9765339605..d1a8af6b69 100644
--- a/src/models/propulsion/FGNozzle.cpp
+++ b/src/models/propulsion/FGNozzle.cpp
@@ -129,6 +129,7 @@ string FGNozzle::GetThrusterValues(int id, const string& delimeter)
 
 void FGNozzle::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGPiston.cpp b/src/models/propulsion/FGPiston.cpp
index 38813b5564..1f8fe0980a 100644
--- a/src/models/propulsion/FGPiston.cpp
+++ b/src/models/propulsion/FGPiston.cpp
@@ -57,7 +57,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGPiston::FGPiston(FGFDMExec* exec, Element* el, int engine_number, struct Inputs& input)
-  : FGEngine(engine_number, input),
+  : FGEngine(exec->gdata(), engine_number, input),
   R_air(287.3),                  // Gas constant for air J/Kg/K
   calorific_value_fuel(47.3e6),  // J/Kg
   Cp_air(1005),                  // Specific heat (constant pressure) J/Kg/K
@@ -249,9 +249,9 @@ FGPiston::FGPiston(FGFDMExec* exec, Element* el, int engine_number, struct Input
     string name = table_element->GetAttributeValue("name");
     try {
       if (name == "COMBUSTION") {
-        Lookup_Combustion_Efficiency = new FGTable(PropertyManager, table_element);
+        Lookup_Combustion_Efficiency = new FGTable(gdata(), PropertyManager, table_element);
       } else if (name == "MIXTURE") {
-        Mixture_Efficiency_Correlation = new FGTable(PropertyManager, table_element);
+        Mixture_Efficiency_Correlation = new FGTable(gdata(), PropertyManager, table_element);
       } else {
         cerr << "Unknown table type: " << name << " in piston engine definition." << endl;
       }
@@ -315,7 +315,7 @@ FGPiston::FGPiston(FGFDMExec* exec, Element* el, int engine_number, struct Input
 // Default tables if not provided in the configuration file
   if(Lookup_Combustion_Efficiency == 0) {
     // First column is thi, second is neta (combustion efficiency)
-    Lookup_Combustion_Efficiency = new FGTable(12);
+    Lookup_Combustion_Efficiency = new FGTable(gdata(), 12);
     *Lookup_Combustion_Efficiency << 0.00 << 0.980;
     *Lookup_Combustion_Efficiency << 0.90 << 0.980;
     *Lookup_Combustion_Efficiency << 1.00 << 0.970;
@@ -332,7 +332,7 @@ FGPiston::FGPiston(FGFDMExec* exec, Element* el, int engine_number, struct Input
 
     // First column is Fuel/Air Ratio, second is neta (mixture efficiency)
   if( Mixture_Efficiency_Correlation == 0) {
-    Mixture_Efficiency_Correlation = new FGTable(15);
+    Mixture_Efficiency_Correlation = new FGTable(gdata(), 15);
     *Mixture_Efficiency_Correlation << 0.05000 << 0.00000;
     *Mixture_Efficiency_Correlation << 0.05137 << 0.00862;
     *Mixture_Efficiency_Correlation << 0.05179 << 0.21552;
@@ -1017,6 +1017,7 @@ string FGPiston::GetEngineValues(const string& delimiter)
 
 void FGPiston::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGPropeller.cpp b/src/models/propulsion/FGPropeller.cpp
index 58b1f55ead..9280203d8f 100644
--- a/src/models/propulsion/FGPropeller.cpp
+++ b/src/models/propulsion/FGPropeller.cpp
@@ -102,13 +102,13 @@ FGPropeller::FGPropeller(FGFDMExec* exec, Element* prop_element, int num)
     name = table_element->GetAttributeValue("name");
     try {
       if (name == "C_THRUST") {
-        cThrust = new FGTable(PropertyManager, table_element);
+        cThrust = new FGTable(gdata(), PropertyManager, table_element);
       } else if (name == "C_POWER") {
-        cPower = new FGTable(PropertyManager, table_element);
+        cPower = new FGTable(gdata(), PropertyManager, table_element);
       } else if (name == "CT_MACH") {
-        CtMach = new FGTable(PropertyManager, table_element);
+        CtMach = new FGTable(gdata(), PropertyManager, table_element);
       } else if (name == "CP_MACH") {
-        CpMach = new FGTable(PropertyManager, table_element);
+        CpMach = new FGTable(gdata(), PropertyManager, table_element);
       } else {
         cerr << "Unknown table type: " << name << " in propeller definition." << endl;
       }
@@ -436,6 +436,7 @@ string FGPropeller::GetThrusterValues(int id, const string& delimeter)
 
 void FGPropeller::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGRocket.cpp b/src/models/propulsion/FGRocket.cpp
index 098b0259ba..d0b69d1076 100644
--- a/src/models/propulsion/FGRocket.cpp
+++ b/src/models/propulsion/FGRocket.cpp
@@ -52,7 +52,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGRocket::FGRocket(FGFDMExec* exec, Element *el, int engine_number, struct Inputs& input)
-  : FGEngine(engine_number, input), isp_function(nullptr), FDMExec(exec)
+  : FGEngine(exec->gdata(), engine_number, input), isp_function(nullptr), FDMExec(exec)
 {
   Load(exec, el);
 
@@ -127,7 +127,7 @@ FGRocket::FGRocket(FGFDMExec* exec, Element *el, int engine_number, struct Input
   // If there is a thrust table element, this is a solid propellant engine.
   thrust_table_element = el->FindElement("thrust_table");
   if (thrust_table_element) {
-    ThrustTable = new FGTable(PropertyManager, thrust_table_element);
+    ThrustTable = new FGTable(gdata(), PropertyManager, thrust_table_element);
     Element* variation_element = el->FindElement("variation");
     if (variation_element) {
       if (variation_element->FindElement("thrust")) {
@@ -333,6 +333,7 @@ void FGRocket::bindmodel(FGPropertyManager* PropertyManager)
 
 void FGRocket::Debug(int from)
 {
+  const auto& debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGRotor.cpp b/src/models/propulsion/FGRotor.cpp
index ab064e59fc..73774e809c 100644
--- a/src/models/propulsion/FGRotor.cpp
+++ b/src/models/propulsion/FGRotor.cpp
@@ -832,6 +832,7 @@ void FGRotor::Debug(int from)
 {
   string ControlMapName;
 
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGTank.cpp b/src/models/propulsion/FGTank.cpp
index 30d09eaed4..539cdafa7e 100644
--- a/src/models/propulsion/FGTank.cpp
+++ b/src/models/propulsion/FGTank.cpp
@@ -49,7 +49,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGTank::FGTank(FGFDMExec* exec, Element* el, int tank_number)
-  : TankNumber(tank_number)
+  : FGJSBBase(exec->gdata()), TankNumber(tank_number)
 {
   string token, strFuelName;
   Element* element;
@@ -510,6 +510,7 @@ void FGTank::bind(FGPropertyManager* PropertyManager)
 
 void FGTank::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGThruster.cpp b/src/models/propulsion/FGThruster.cpp
index 9b70a5d2cb..3b05a26028 100644
--- a/src/models/propulsion/FGThruster.cpp
+++ b/src/models/propulsion/FGThruster.cpp
@@ -72,7 +72,7 @@ FGThruster::FGThruster(FGFDMExec *FDMExec, Element *el, int num ): FGForce(FDMEx
 
   element = thruster_element->FindElement("location");
   if (element)  location = element->FindElementTripletConvertTo("IN");
-  else          cerr << fgred << "      No thruster location found." << reset << endl;
+  else          cerr << gdata().fgred << "      No thruster location found." << gdata().reset << endl;
 
   SetLocation(location);
 
@@ -175,6 +175,7 @@ string FGThruster::GetThrusterValues(int id, const string& delimeter)
 
 void FGThruster::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGTransmission.cpp b/src/models/propulsion/FGTransmission.cpp
index 4c756a7a68..4a94bc7b30 100644
--- a/src/models/propulsion/FGTransmission.cpp
+++ b/src/models/propulsion/FGTransmission.cpp
@@ -53,6 +53,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGTransmission::FGTransmission(FGFDMExec *exec, int num, double dt) :
+  FGJSBBase(exec->gdata()),
   FreeWheelTransmission(1.0),
   ThrusterMoment(1.0), EngineMoment(1.0), EngineFriction(0.0),
   ClutchCtrlNorm(1.0), BrakeCtrlNorm(0.0), MaxBrakePower(0.0),
@@ -176,6 +177,7 @@ bool FGTransmission::BindModel(int num)
 
 void FGTransmission::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGTurbine.cpp b/src/models/propulsion/FGTurbine.cpp
index 75b01106e0..29c952a091 100644
--- a/src/models/propulsion/FGTurbine.cpp
+++ b/src/models/propulsion/FGTurbine.cpp
@@ -57,7 +57,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGTurbine::FGTurbine(FGFDMExec* exec, Element *el, int engine_number, struct Inputs& input)
-  : FGEngine(engine_number, input), FDMExec(exec)
+  : FGEngine(exec->gdata(), engine_number, input), FDMExec(exec)
 {
   Type = etTurbine;
 
@@ -632,6 +632,7 @@ int FGTurbine::InitRunning(void)
 
 void FGTurbine::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/src/models/propulsion/FGTurboProp.cpp b/src/models/propulsion/FGTurboProp.cpp
index 4cad50b408..6e1d9aedd3 100644
--- a/src/models/propulsion/FGTurboProp.cpp
+++ b/src/models/propulsion/FGTurboProp.cpp
@@ -60,7 +60,7 @@ CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 FGTurboProp::FGTurboProp(FGFDMExec* exec, Element *el, int engine_number, struct Inputs& input)
-  : FGEngine(engine_number, input),
+  : FGEngine(exec->gdata(), engine_number, input),
     ITT_N1(NULL), EnginePowerRPM_N1(NULL), EnginePowerVC(NULL),
     CombustionEfficiency_N1(NULL)
 {
@@ -148,18 +148,18 @@ bool FGTurboProp::Load(FGFDMExec* exec, Element *el)
       // ugly hack but the functionality is obsolete and will be removed some
       // time in the future.
       table_element->SetAttributeValue("name", string("propulsion/engine[#]/") + name);
-      EnginePowerVC = new FGTable(PropertyManager, table_element,
+      EnginePowerVC = new FGTable(gdata(), PropertyManager, table_element,
                                   to_string((int)EngineNumber));
       table_element->SetAttributeValue("name", name);
       cerr << table_element->ReadFrom()
            <<"Note: Using the EnginePowerVC without enclosed <function> tag is deprecated"
            << endl;
     } else if (name == "EnginePowerRPM_N1") {
-      EnginePowerRPM_N1 = new FGTable(PropertyManager, table_element);
+      EnginePowerRPM_N1 = new FGTable(gdata(), PropertyManager, table_element);
     } else if (name == "ITT_N1") {
-      ITT_N1 = new FGTable(PropertyManager, table_element);
+      ITT_N1 = new FGTable(gdata(), PropertyManager, table_element);
     } else if (name == "CombustionEfficiency_N1") {
-      CombustionEfficiency_N1 = new FGTable(PropertyManager, table_element);
+      CombustionEfficiency_N1 = new FGTable(gdata(), PropertyManager, table_element);
     } else {
       cerr << el->ReadFrom() << "Unknown table type: " << name
            << " in turboprop definition." << endl;
@@ -176,7 +176,7 @@ bool FGTurboProp::Load(FGFDMExec* exec, Element *el)
   // default table based on '9.333 - (N1)/12.0' approximation
   // gives 430%Fuel at 60%N1
   if (! CombustionEfficiency_N1) {
-    CombustionEfficiency_N1 = new FGTable(6);
+    CombustionEfficiency_N1 = new FGTable(gdata(), 6);
     *CombustionEfficiency_N1 <<  60.0 << 12.0/52.0;
     *CombustionEfficiency_N1 <<  82.0 << 12.0/30.0;
     *CombustionEfficiency_N1 <<  96.0 << 12.0/16.0;
@@ -584,6 +584,7 @@ void FGTurboProp::bindmodel(FGPropertyManager* PropertyManager)
 
 void FGTurboProp::Debug(int from)
 {
+  auto debug_lvl = gdata().debug_lvl;
   if (debug_lvl <= 0) return;
 
   if (debug_lvl & 1) { // Standard console startup message output
diff --git a/tests/unit_tests/FGJSBBaseTest.h b/tests/unit_tests/FGJSBBaseTest.h
index a493f89f65..d176c49331 100644
--- a/tests/unit_tests/FGJSBBaseTest.h
+++ b/tests/unit_tests/FGJSBBaseTest.h
@@ -6,6 +6,9 @@
 class FGJSBBaseTest : public CxxTest::TestSuite, public JSBSim::FGJSBBase
 {
 public:
+  CommonData c;
+  FGJSBBaseTest() : JSBSim::FGJSBBase(c) {}
+
   void testMessages() {
     const std::string myMessage = "My message";
     std::set<int> mesId;