The 'Ask The Pilot' columnist at Salon says yes.
… “United 93″ succeeds where almost every other movie fails. For the record, I counted about 15 minor gaffes, ranging from poorly rendered air traffic control lingo to an errant shot of an Airbus A320 standing in as the United 757. But the reconstructions are, if not flawlessly spot-on, close enough to keep a known pedant like me from listing the bloopers here. Even the background chatter between pilots and air traffic controllers is, in many instances, taken verbatim from actual ATC recordings. The overall lack of miscues is doubtless owed to the use of actual controllers and air crew staff as cast members, including United Airlines pilot J.J. Johnson as Capt. Jason M. Dahl. The most touching bit of realism may be the moment when, preparing to eat his breakfast in the cockpit, first officer LeRoy Homer, played by commercial pilot Gary Commock, removes a bottle of hot sauce from his flight kit. I smiled at that, familiar with the popularity of those little red bottles among fliers — a requisite flight bag item no less crucial than maps, charts and manuals.