Mid-air blowout jet had been restricted over warning light
The Boeing airliner that suffered an in-flight blowout over Oregon was not being used for journeys to Hawaii after a warning light that could have indicated a pressurisation problem lit up on three different flights, a US official said.
Alaska Airlines decided to restrict the aircraft from long flights over water so that the plane “could return very quickly to an airport” if the warning light reappeared, said Jennifer Homendy, chair of the US National Transportation Safety Board (NTSB).
Ms Homendy cautioned that the pressurisation light might be unrelated to Friday's incident in which a plug covering an unused exit door blew off the Boeing 737 Max 9 as it cruised about three miles over Oregon.
The warning light came on during three previous flights: on December 7, January 3 and finally on January 4, the day before the door plug broke off.
Ms Homendy said she did not have all the details regarding the December 7 incident but specified the light came on during a flight on January 3 and on January 4 after the plane had landed.
The NTSB said the lost door plug was found on Sunday near Portland, Oregon, by a school teacher who discovered it in his back garden and sent two photos to the safety board.
Investigators will examine the plug, which is 26 by 48 inches and weighs 63 pounds, for signs of how it broke free.
Investigators will not have the benefit of hearing what went on in the cockpit during the flight. The cockpit voice recorder – one of two socalled black boxes – recorded over the flight's cockpit footage after two hours, Ms Homendy said.
At a news conference on Sunday night, Ms Homendy provided new details about the chaotic scenes that unfolded on the plane as it travelled from Portland to Ontario, California.
The explosive rush of air damaged several rows of seats and pulled insulation from the walls. The cockpit door flew open and banged into a lavatory door.
The force ripped the headset off the co-pilot and the captain lost part of her headset. A quick reference checklist kept within easy reach of the pilots flew out of the open cockpit.
The plane made it back to Portland, however, and none of the 171 passengers and six crew members was seriously injured.
Hours after the incident, the US Federal Aviation Administration (FAA) ordered the grounding of 171 of the 218 Max 9s in operation, including all those used by Alaska Airlines and United Airlines, until they can be inspected.
Alaska Airlines, which has 65 Max 9s, and United, with 79, are the only US airlines to fly that particular model of Boeing’s workhorse 737.
United said it was waiting for Boeing to issue a “multi-operator message”, which is a service bulletin used when multiple airlines need to perform similar work on a particular type of plane.
Boeing is working on the bulletin but had not yet submitted it to the FAA for review and approval, according to a source. It can take a couple of days.
Hours after the incident, the US Federal Aviation Administration ordered the grounding of 171 Max 9s