diff --git a/src/Main/main.cxx b/src/Main/main.cxx
index aed183c37..b1b9e32e8 100644
--- a/src/Main/main.cxx
+++ b/src/Main/main.cxx
@@ -105,20 +105,7 @@ extern int _bootstrap_OSInit;
 // What should we do when we have nothing else to do?  Let's get ready
 // for the next move and update the display?
 static void fgMainLoop( void ) {
-    
-    static SGConstPropertyNode_ptr longitude
-        = fgGetNode("/position/longitude-deg");
-    static SGConstPropertyNode_ptr latitude
-        = fgGetNode("/position/latitude-deg");
-    static SGConstPropertyNode_ptr altitude
-        = fgGetNode("/position/altitude-ft");
-    static SGConstPropertyNode_ptr vn_fps
-        = fgGetNode("/velocities/speed-north-fps");
-    static SGConstPropertyNode_ptr ve_fps
-        = fgGetNode("/velocities/speed-east-fps");
-    static SGConstPropertyNode_ptr vd_fps
-        = fgGetNode("/velocities/speed-down-fps");
-      
+          
     static SGPropertyNode_ptr frame_signal
         = fgGetNode("/sim/signals/frame", true);
 
@@ -145,11 +132,7 @@ static void fgMainLoop( void ) {
     timeMgr->computeTimeDeltas(sim_dt, real_dt);
 
     // update magvar model
-    globals->get_mag()->update( longitude->getDoubleValue()
-                                * SGD_DEGREES_TO_RADIANS,
-                                latitude->getDoubleValue()
-                                * SGD_DEGREES_TO_RADIANS,
-                                altitude->getDoubleValue() * SG_FEET_TO_METER,
+    globals->get_mag()->update( globals->get_aircraft_position(),
                                 globals->get_time_params()->getJD() );
 
     // Run ATC subsystem
@@ -447,16 +430,11 @@ static void fgIdleFunction ( void ) {
         globals->set_mag( magvar );
 
 
-                                    // kludge to initialize mag compass
-                                    // (should only be done for in-flight
-                                    // startup)
+        // kludge to initialize mag compass
+        // (should only be done for in-flight
+        // startup)
         // update magvar model
-        globals->get_mag()->update( fgGetDouble("/position/longitude-deg")
-                                    * SGD_DEGREES_TO_RADIANS,
-                                    fgGetDouble("/position/latitude-deg")
-                                    * SGD_DEGREES_TO_RADIANS,
-                                    fgGetDouble("/position/altitude-ft")
-                                    * SG_FEET_TO_METER,
+        globals->get_mag()->update( globals->get_aircraft_position(),
                                     globals->get_time_params()->getJD() );
         double var = globals->get_mag()->get_magvar() * SGD_RADIANS_TO_DEGREES;
         fgSetDouble("/instrumentation/heading-indicator/offset-deg", -var);