Crashing with Sulla happens because the landing gear take a bit longer to lower than other planes and they have a habit of sometimes starting to lower later than you thought they would (only by 0.25-0.75 seconds but this is usually enough as they already take long enough to go down that it's cutting it close anyway)
This is the ONLY reason it happens, I've tested it. Try landing on the eastern runway on sandblasted (the one that's behind the pyramid) and come in from the front. If you watch your shadow and only land once the shadow of your landing gear has been fully deployed for about a tenth to a quarter of a second you will never crash
Sometimes it looks like your landing gear clipped through because you touched down when they were 99% down but not yet an actual solid thing on your plane that collides so you belly land instead
Um. Well this post is a year old, but I'm pretty sure there's more going on here than he suggests. The reason I say this is because there is one map, I forget the name, it's a terrain control map with a bigass crater in the middle with a control point in it. On this map, the airbases are right next to the mech hangars, and so there is an extremely long stretch of flat, paved road that eventually transitions into the runway for the airbase.
There have been several occasions where I've asked members of my team to watch me while I land as they're coming out of the mech hangar. I fly low and slow for several seconds over this flat ground, past the mech hangar, leaving plenty of time for the landing gear to lower itself. And after I touch what I think is my main gear down, then explode spectacularly the moment the nose lowers and the plane has its full belly resting on the pavement, they all say my landing gear has been retracted the whole time and I did a graceful bellyflop.
Even if this was the case, it's really not acceptable because on most maps the runways are relatively short. You don't have a lot of time to float over the runway waiting for your gear to extend, you'll often end up overshooting it or running off the edge.
Stupid question: Why can't we just make the landing gear a toggle with the crouch key, so I can lower it manually in advance instead of relying on the game to detect my proximity to the ground?