This crash is theoretically frame perfect, meaning the steps to recreate it will not always work. Side note: this is also a bug in the base game.
-After multiple UFOs are detected, intercept 2 or more of them with interceptors with equal ETA
-When they intercept, auto resolve it (I'm not sure if this happens with engaging)
-Auto resolve the second one, too
-If they intercepted at the exact same time, the game should crash 100% of the time
I couldn't get a save game or screen shot because my computer sucks and crashed, apparently having Google and Xenonauts open crashes my laptop EVERYTHING CRASHES MY LAPTOP (completely unrelated to the game).