If you were scheduled to fly on a United Boeing 757 yesterday afternoon or evening, you likely encountered a delay or cancellation. In a move reminiscent of American Airlines’ grounding of their entire MD-80 fleet when found to be out of FAA compliance, UA voluntary grounded its 97 757 jets to perform checks to air-data computers.
Each inspection takes about an hour, but that still meant quite a few late departures and scrapped flights. Upon discovery that it had not been following FAA-mandated procedures for checking air-data computers, UA sprung into action immediately, likely driven by a desire to avoid $25,000/flight fines for knowingly operating while being out of compliance (that was AA's problem). Air-data computers track information including air pressure and speed and feed it into auto-pilot.
Most inspections are now complete and no problems have been found. Some 757s at airports beyond the reach of proper inspection equipment are still grounded for the time being. Continental’s 65 757s were not affected.