ubiq,
“No techum in the air, though if takes off on shabbos is a problem on the runway. Even if argue that are 10 tefachuim off the ground, if plane sitting on ground may be a problem”
The actual flying might not be a techum issue. However, they do have a tchum issue once they arrive, as they are coming from out of the tchum and may need to remain in place.
“Causing the plane to burn more fuel?”
This would be “marbe B’shiurim”. However, its unlikely that any one person would cause a commercial airliner to burn more fuel.