Only ever had this happen with the civilian Mi-8 in Dogs of War, but it seems when the AI pilot lands, there's a good chance of anyone on board being killed for some reason (ranging from Razor members to AI under your command to Lopotev himself). I'll test to see if it happens in other non DoW situations.
Also, a related problem, is that Razor team and any nearby units under your command Spoiler:
just magically appear in the chopper after capturing Lopotev on Skalisky island.
Aside from immersion, the problem with this is that if any team members are heavily wounded and you haven't had time to heal them before being teleported to the chopper, they often bleed to death en route to landing zone and pop out dead.