Why "In order to travel" is not correct here?
I think it should be accepted - probably a forgotten alternative.
Why "For travelling it is not necessary to own a plane" is wrong?
I am understanding in the meantime why it is not correct, but how would I translate into Turkish "It is not necessary to own a plane for travelling."?
It is not necessary to own a plane in order (için) to travel.
The same Turkish sentence. No difference. The difference is in the English phrasing.