Airfield Problem !!!!

[dinothenino]

Hello my name is dinos and i am a newbie in sust 3.
I begun step by step to make a map which includes an airfield.
I put the airfield i also add the planes as passengers but i cannot take them off.
What am i doing wrong?
Also another question,what if my planes that are in my airfield are shot down how am i supposed to have the same type
again reappear in my airfield?

Please help me with your knowledge,
thank you in advance
Dinos