Another thing I've been working on for a little while now, as part of my object improvement binge, is making various shelters useable by re-jigging too-simplistic or too-all-encompassing collision objects. Take these shelters here, the ones with a camo net roof and toughened sides. Previously, the collision object encompassed THE WHOLE THING, making it impossible to put a plane into else it blow up. For these I've split the collision object into two, each covering just the built-up sides only. (The roof and thin supports are treated as not there at all, collision wise, so that you can shoot up stuff inside.) This means you can start a mission from inside one (provided the wingtips don't touch the sides, as the I-16 is safe to do.) And anything inside can be shot up without first having to destroy the shelter itself.
This screenie is taken from the FMB for a mission made for Mixx's Khalkin Gol map. Here you and a wingman start from spawn points shown as magenta 'ghost' plane place markers. Originally, both spawn points were safely OUTSIDE the shelters (else you'd explode at mission start). Here I've placed one inside its shelter. And you can see a couple of stationary I-16s placed in their shelters, so that you can see how they fit comfortably enough for the player to taxi out from inside one.
Additionally, these shelters were turned around by the mission maker, with the lower back side roof facing outward. (I've left it was first placed for that shelter next to the spawn point I left outside.) Perhaps this was to emphasize their non functionality as regards planes? I point this out so that now mission makers will be able to consider their actual use for planes, instead of as mostly decorations.
For other such shelters, netting and hangars, I've been altering the collision boxes so that planes can safely venture within them.