Frederic Bouvier:

Melchior spotted a problem where we can crash an airplane into the
beacon's beam. The patch below enable to mask out a branch from HOT
traversal, whatever the animation.

The beacon.xml file is also included. It has a
<enable-hot type="bool">false</enable-hot> in a halo branch

simgear/scene/model/animation.cxx

@@ -182,6 +182,11 @@ SGAnimation::SGAnimation (SGPropertyNode_ptr props, ssgBranch * branch)
     : _branch(branch)
 {
     _branch->setName(props->getStringValue("name", 0));
+    if ( props->getBoolValue( "enable-hot", true ) ) {
+        _branch->setTraversalMaskBits( SSGTRAV_HOT );
+    } else {
+        _branch->clrTraversalMaskBits( SSGTRAV_HOT );
+    }
 }
 
 SGAnimation::~SGAnimation ()