Alaska Airlines allowed the Boeing plane that had a mid-air blowout this week to fly despite warnings from a cabin-pressurisation system, according to US investigators.
The National Transportation Safety Board (NTSB), the US’ chief accident investigator, announced on Monday that warning lights were triggered on the brand-new Boeing 737 Max 9 on three flights. The alarms came on two consecutive days before the plane suffered a terrifying fuselage blowout on Friday.
The fact that the company stopped flying the aircraft over the Pacific Ocean to Hawaii due to warnings – yet kept it flying over land – raises the question if the jet should have been in the air at all.
A plug covering a spot left for an emergency door tore off the plane as it flew 4,800m (16,000 feet) above Oregon.
Maintenance crews checked the plane and cleared it to fly, but the airline decided not to use it for the long route to Hawaii over water so that it “could return very quickly to an airport” if the warning light reappeared, according to Jennifer Homendy, chair of the NTSB.
Friday’s flight was headed from Oregon to Southern California, and made it back to Portland without serious injury to any of the 171 passengers and six crew members.
United Airlines and Alaska Airlines have said they found loose parts on multiple grounded Boeing 737 Max 9 aircraft, raising new concerns among industry experts about the manufacturing process for the passenger planes.
The Federal Aviation Administration (FAA) grounded 171 Max 9 planes worldwide after a cabin panel blew off an Alaska-operated plane in midair on Friday, forcing the pilots to make an emergency landing.
The panel that blew out on Friday’s Alaskan flight was a door plug and the FAA ordered operators to ground all aircraft with the same configuration.
With 79 Max 9 planes, United has the largest fleet of the aircraft in question. Alaska has 65 of the planes, while the remainder are operated by Turkish Airlines, Panama’s Copa Airlines and Aeromexico.
The midair incident has raised concerns about the production process and quality control for the Max 9. The model is used by relatively few airlines but the 737 Max family of aircraft has been dogged by controversy since the entire global fleet was grounded in March 2019 after two crashes in the space of six months killed 346 people.
Boeing said it was staying in close contact with Max 9 operators and would help customers address any findings during the latest inspections.
On Monday, the FAA announced that it approved a road map for carriers to complete inspections that include both left and right door plugs, components and fasteners. It said planes would remain grounded until operators complete the “enhanced inspections”.