Alaska Airlines has grounded dozens of Boeing 737 MAX 9 jets for safety checks after a cabin panel blowout forced a newer airplane loaded with passengers to make an emergency landing.

The piece of fuselage tore off from the left side of the jet as it climbed out of Portland, Oregon, en route to Ontario, California, on Friday, forcing pilots to turn back and land safely with 171 passengers and six crew on board.

It is the latest mishap involving Boeing’s bestselling model, which was grounded for almost two years following crashes in 2018 and 2019, and comes as Boeing and a major supplier are grappling with a succession of production and quality problems.

There were no immediate indications of the cause of the apparent structural failure nor any reports of injuries.

Airline CEO Ben Minicucci said in a statement that its fleet of 65 similar planes would be returned to service only after precautionary maintenance and safety inspections, which he expected to be completed in the “next few days.”

U.S. aviation authorities announced an investigation.

The National Transportation Safety Board said Saturday that a team of experts in structures, operations and systems would arrive on the scene later that day.

Boeing also said it was looking into the incident.

“We are working to gather more information and are in contact with our airline customer,” Boeing said.

“We’d like to get down”

Flight 1282 had reached just over 4,000 meters (13,100 feet) when the blowout happened, according to FlightRadar24.

“We’d like to get down,” the pilot told air traffic control, according to a recording posted on liveatc.net.

“We are declaring an emergency. We do need to come down to 10,000,” the pilot said, referring to the initial staging altitude for such emergencies, below which breathing is considered possible for healthy people without extra oxygen.

Social media posts showed oxygen masks deployed and a portion of the aircraft’s side wall missing.

Passenger photos appeared to show that a section of the fuselage sometimes used for an optional rear midcabin exit door had been torn away, leaving a door-shaped gap.

People sit on a plane next to a missing window and portion of a side wall of an Alaska Airlines Flight 1282, which had been bound for Ontario, California, from Portland, Oregon, on Jan. 5, 2024. (Instagram/@strawberrvy via Reuters)

People sit on a plane next to a missing window and portion of a side wall of an Alaska Airlines Flight 1282, which had been bound for Ontario, California, from Portland, Oregon, on Jan. 5, 2024. (Instagram/@strawberrvy via Reuters)

The extra door is typically installed by low-cost airlines using extra seats that require more paths for evacuation.

However, those doors are permanently “plugged,” or deactivated, on Alaska Airlines jets.

The new MAX 9 was delivered to Alaska Airlines in late October and certified in early November, according to FAA data.

Production snags

“Whenever you have a rapid decompression such as this, it’s a major safety event,” said Anthony Brickhouse, an air safety expert at Embry-Riddle Aeronautical University.

“I can’t imagine what these passengers experienced,” he said. “It would have been loud. The wind would be rushing through that cabin. It was a probably pretty violent situation, and definitely a scary situation.”

The incident shows the importance of passengers keeping their seatbelts buckled while seated in an airplane, even if the fasten-seatbelt light is off, Brickhouse said, noting that the oxygen mask system appeared to have functioned properly.

Reports said the seat next to the left-hand panel, which contains an ordinary passenger window, was unoccupied.

“This is a very, very serious situation and it could have been a lot worse,” he said. “If someone had been sitting in that seat, and they weren’t buckled in, it would have been a different situation.”

The 737 MAX was grounded for 20 months worldwide after two fatal crashes in 2018 and 2019 linked to poorly designed cockpit software killed 346 people in Ethiopia and Indonesia. Boeing is awaiting certification of its smaller 737 MAX 7 and larger MAX 10.

China’s aviation regulator is conducting an emergency meeting to consider a response to the incident, including a possible new grounding of the Boeing MAX fleet in the country, Bloomberg news reported on Saturday.

China was the first country to ground the MAX in 2019 and only recently started accepting new deliveries, although domestic services using the plane resumed in January last year.

Last week, Boeing said it was urging airlines to inspect all 737 MAX airplanes for a possible loose bolt in the rudder control system.

The FAA said it was closely monitoring Boeing 737 MAX inspections and would consider additional action if more loose or missing hardware was found.