Codextro explained concisely on the eugen forums how infantry survivors from a destroyed transport are determined, so I’ll just quote him:
Passenger damage is simple, overkill damage from killing the vehicle is applied to the passengers.
0AV takes double damage from AP, so an 8 AP hit (KE or HEAT), does 16 damage to a humvee, killing the 5 HP humvee and everyone inside.
Fuchs takes 1 damage/AP (KE or HEAT), a 20 AP hit does 10 to kill the Fuchs and 10 to kill the passengers
XA-180 takes (x-2)/2+1 damage from KE, and (x-2)/2+1 for the first 10 HEAT AP over AV, and 1 per AP afterwards. To get 20 damage you need 40 KE (not possible with any unit in the game), or 26 HEAT.
My testing shows these numbers are consistent, feel free to verify it.
15 man squads can survive a heli crash because the crash only does 11 damage to passengers.
The helo crash damage could be 12 instead of 11, I’m not sure and it’s too minor to bother testing. Regardless of which is true, codextro’s summary is very good.