DY > He was davening. I guess you think that’s inappropriate if it’s not outdoors??
?! Look up my posts above and review references therein of multiple gedolim pointing various nekudos what can be inappropriate, but you seem to be more interested in a hypothetical crazt flight attendant rather than in typical cases. If you do want to bring Covid into the picture, I have no problem with him davening, in fact, it becomes a medauraita rather than mid Rabonan! We would also need to indeed see why he is on the plane. If there is a mitzva involved, fine. But if he is on the way to a non-essential trip, then davening may be a sheretz b’yado.