Yesterday I and another player were sitting at V58 on the Mid-Mesa map which had been under attack off and on for quite awhile.
We were both in tanks sitting there looking out toward the spawn when the VH near the map room spontaneously blew up. I was sitting on that hanger pad so I could watch the map room at the time. There were no aircraft in the area, no dar bar, no sounds of bombs falling, no ground fire, no flashing, no warning sirens... nothing. Another player who was in God mode in the tower saw it too.
A few minutes later the hanger across from the spawn hanger did the same thing.
It's hard enough defending these bases at times without giving the enemy the added advantage of spotaneously combusting hangers.