Stationary planes appearing on enemy bases

[IceFire]

I'm guessing the server is stock but the game is modded? I don't otherwise recognize the ground textures, clouds, or the smoke. Probably a compatibility issue between the mod and stock 4.11.1. There are ton of mod/stock compatibility issues on spawning (my favourite is people selecting a home base and ending up halfway across the map... *sigh*) so I'm not surprised that it extends into some other weirdness.