It has happened to be a few times as well. I thought it was a bug in the radar tower destruction modeling. I assume I have bent the prop on a few buildings as well, but when they are down, the overall frame of the building still remains and makes it easier to avoid. The radar tower, when destroyed, is completely down. As a result, your flight path looks clear and then BANG you hit the "shadow" of the previously standing antenna.
Come to think of it... same thing happens when driving a GV across a gun emplacement that has been destroyed. The gun pad is empty, but sure as you try to drive across it, you hit an invisable solid object and come to an abrupt halt; thereby, ramming your cartoon face through the windshield becuase you neglected to wear your seatbelt.
In fact, I think you should get a GV pilot wound when you hit objects like that at full speed.
