United passengers face delays after 757s grounded
United Airlines customers can still expect delays Wednesday after the airline grounded its entire fleet of Boeing 757 aircraft Tuesday due to maintenance checks on aircraft computers, a company spokesman confirmed.
The grounding caused at least 17 flights to be canceled Tuesday and an unspecified number of delays. No cancellations were expected Wednesday.
Spokesman Charlie Hobart said United was conducting “unscheduled maintenance” on the fleet of 96 aircraft. “Further operational checks are necessary following a modification to the 757 air data computers,” Hobart said.
Airline spokeswoman Megan McCarthy said United grounded the Boeing 757 aircraft because the carrier determined that it had not completed operational checks after updating air data computers following a 2004 federal directive.
United said checks began “immediately” after the airline recognized the oversight during routine quality assurance checks Tuesday afternoon. Each check is expected to take between 60 and 90 minutes.
The airline will provide additional aircraft where available and will place affected customers on other flights and airlines tonight and tomorrow when possible, Hobart said.
“We are asking customers to check their flight status online before leaving for O'Hare,” he said. “They can also check online to see if they are scheduled on a 757.”
Although the aircrafts have been grounded, the flight systems have remained fully functional, according to United.
A spokeswoman with the Federal Aviation Administration said FAA was aware of the grounding, but that United's actions were not forced by the agency.
“The action is by United,” she said. “It is their decision.”
The 182-seat 757 is primarily used for domestic flights, Hobart said.
United Continental Holdings Inc.'s fleet of 62 Continental 757s has not been affected.
The maintenance involves installing new circuit breakers, relays, and related components, and making various wiring changes in and between the flight deck and main equipment center.
According to the published directive, the actions were necessary to ensure that the flight crew is able to silence an erroneous overspend or stall warning. A persistent erroneous warning could confuse and distract the flight crew and lead to an increase in the flight crew's workload. Such a situation could lead the flight crew to act on hazardously misleading information, which could result in loss of control of the airplane, according to the directive.
• Daily Herald news services contributed to this report