I have taken one hit before, no damage, ended sortie, and then see "xxx" shot you down.
It all depends on
where you are when you end sortie.
In friendly territory (closest base is a friendly one, this includes Task Groups!)
On pavement (town/base): You can always end sortie safely.
On other ground and undamaged: Safe landing when no enemy is around (within 6k). When an enemy is close, you will get a ditch.
Other ground and (critically?) damaged: Safe landing when no enemy is around. "Crash" when an enemy around, he may also get a kill on you when you are in proxy kill range. (If the player who damaged you in the forst place is still in sortie, he will always get the kill then, no matter which distance)
In enemy territory (closest base is a a hostile one, again, this includes Task Groups!)
In all cases, it's assumed you are not moving when you end sortie.
Pavement: Doesn't matter anymore. It's always:
No enemy is around: Safe landing, even when damaged. If an enemy is within 6k, you get a captured. If he's inside proxy kill range, he will get a kill on you.