diff --git a/src/Main/fg_init.cxx b/src/Main/fg_init.cxx
index daf286844..4556c9e57 100644
--- a/src/Main/fg_init.cxx
+++ b/src/Main/fg_init.cxx
@@ -1820,6 +1820,7 @@ void fgReInitSubsystems()
         fgSetBool("/sim/freeze/master", true);
     }
     fgSetBool("/sim/crashed", false);
+    fgSetBool("/sim/initialised", false);
 
     // Initialize the FDM
     fgInitFDM();
@@ -1843,5 +1844,6 @@ void fgReInitSubsystems()
     if ( !freeze ) {
         fgSetBool("/sim/freeze/master", false);
     }
+    fgSetBool("/sim/initialised", true);
 }
 
diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index 08fa6f202..365051385 100644
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -1350,6 +1350,8 @@ static void fgIdleFunction ( void ) {
     // printf("idle state == %d\n", idle_state);
 
     if ( idle_state == 0 ) {
+        fgSetBool("sim/initialised", false);
+
         // Initialize the splash screen right away
         if ( fgGetBool("/sim/startup/splash-screen") ) {
             fgSplashInit(fgGetString("/sim/startup/splash-texture"));
@@ -1433,6 +1435,7 @@ static void fgIdleFunction ( void ) {
     if ( idle_state == 1000 ) {
         // We've finished all our initialization steps, from now on we
         // run the main loop.
+        fgSetBool("sim/initialised",true);
 
         fgRegisterIdleHandler(fgMainLoop);
     } else {