Traveling and wearing a VPAP

My father has had a VPAP for about 3 months now. He is planning a trip from Chicago to Arizona. We are hearing conflicting information on whether he has to wear the VPAP while flying or not. Supposedly there are two different atmostpheres in the airplane? I don't even know if this is good information. He is very comfortable with flying - not anxious or nervous, does it all the time. It is only a 4 hour flight - not an international flight. He currently only uses this for sleep. Does anyone use their CPAP when flying? Does it help and does anyone know where to go to find out if this is legit information?

pbj461 wrote: We are hearing conflicting information on whether he has to wear the VPAP while flying or not.

only if sleeping.

He doesn't have to wear it on the airplane unless asleep.

He should not, however, check his VPAP. He should carry it aboard. The airline has to let him, and it doesn't count as a carryon.

Does he wear the VPAP while he is awake at home? If not, why would he wear it on the plane? The unit is made to be used while asleep.