A couple of questions about the Night Moves:
Does Wheels down always trigger Behind ennemy line or only if “you’re in immediate danger” is chosen?
How can you be Behind enemy lines whithout being going down because of Enemy Fire (then you’re always in combat zone, so always roll guts.)?
Follow the fiction: not even chosing “Your landing puts you in immediate danger” should always trigger Behind Enemy Lines; for example, if they have to roll Wheels Down to land on their airbase, it doesn’t matter what they choose, they aren’t behind enemy lines.
As for how can someone be behind enemy lines without being subjected to enemy fire, again follow the fiction; maybe their plane was damaged and they choose “Your plane suffers a minor mechanical failure” while wayfinding, so that the plane goes down near the target. This could mean to land Behind Enemy Lines (since they were over the target).
/sub
“Immediate danger” can take many forms. If they make it back to the airbase, maybe it means the NKVD comes calling for an Informal Interview. A wrecked plane means carelessness with the people’s machinery, which, worst case, is a criminal offense.
If you land your plane behind enemy lines the move is triggered, regardless of the reason. Follow the fiction.