--- SimGear-0.3.10/simgear/scene/sky/sky.cxx~	2007-03-30 12:08:35.000000000 +0200
+++ SimGear-0.3.10/simgear/scene/sky/sky.cxx	2007-03-30 12:08:36.000000000 +0200
@@ -33,6 +33,8 @@
 #include "sky.hxx"
 #include "cloudfield.hxx"
 
+SGSky *thesky = NULL;
+
 // Constructor
 SGSky::SGSky( void ) {
     effective_visibility = visibility = 10000.0;
@@ -47,6 +49,9 @@
     // ramp_down = 4.0;
 
     in_cloud  = -1;
+
+    if (thesky == NULL)
+        thesky = this;
 }
 
 
@@ -55,6 +60,9 @@
 {
     for (unsigned int i = 0; i < cloud_layers.size(); i++)
         delete cloud_layers[i];
+
+    if (this == thesky)
+        thesky = NULL;
 }