FAA Orders Grounding of Some Boeing 737 MAX 9 Jets After Emergency Landing

The Federal Aviation Administration ordered a temporary grounding and immediate inspections of dozens of Boeing 737 MAX jets, after one of the planes made an emergency landing when a section of the aircraft ripped away in midair.

Passengers and flight attendants described a harrowing incident during an Alaska Airlines flight on a 737 MAX 9 jet Friday night that left a gaping hole at 16,000 feet in the sky. Alaska and United, two of the biggest users of the jets, canceled dozens of flights each on Saturday but said inspections were under way.

The FAA said its directive would affect about 171 of the MAX 9 jets, which is a bigger variant of the MAX-8 that was involved in two fatal accidents. The inspections will take between four and eight hours per aircraft, which then can return to service. The National Transportation Safety Board said it is also investigating and has sent a team to inspect the plane in Portland, Ore.

Alaska said it had canceled 160 flights Saturday, affecting 23,000 passengers, and that cancellations would likely continue through at least midweek as it works to make sure its inspections meet the FAA’s requirements.

The piece of the Alaska Airlines plane that was torn off during Friday’s flight was a panel that plugs an optional emergency exit on the MAX 9, used by airlines such as Alaska that have fewer seats and don’t need the additional exit. There are about 200 MAX 9 models in service with airlines around the world.

A door plug panel that blows off could cause injuries to passengers and crew, hit the plane, or potentially cause a loss of control, the FAA said in its directive. The FAA said that potential for a similar problem “is likely to exist or develop in other products of the same type design.”

Boeing, which has been dogged by quality issues, said that it agrees with the FAA’s decision and that it has a technical team aiding the NTSB’s investigation. “Safety is our top priority and we deeply regret the impact this event has had on our customers and their passengers,” the company said.

The Alaska jet took off Friday evening from Portland carrying more than 170 passengers and six crew. It had reached an altitude of about 16,000 feet when it had to make an emergency U-turn and return to the airport.

The plane was almost brand new. It entered commercial service in November and had flown fewer than 150 flights since, according to Flightradar24, a flight tracking service.

About 20 minutes into the flight, a chunk of the cabin wall blew out, according to a passenger who was aboard. The pressure rapidly dropped in the cabin, causing objects like a cellphone to fly out the opening. A toddler’s shirt was ripped off him and flew into the night sky, the passenger said.

Photos and video that passengers posted on social media showed a gaping opening in the plane. Oxygen masks dangled down. The union that represents Alaska’s flight attendants described an “explosive” depressurization and said one flight attendant sustained minor injuries.

Some aviation-safety officials and executives said a silver lining in the situation was that the episode happened around 16,000 feet and not at a higher cruising altitude.

As a plane ascends, the difference between the pressure inside of the cabin and outside increases. If an opening emerges during flight, air in the plane will rush out. That could send objects hurling through the cabin and, at least potentially, pull out passengers. The effect is more intense at higher altitudes.

At roughly 16,000 feet, the air that flowed out of the Alaska jet through the door would have felt like a very strong wind, according to John Cox, a former pilot who now runs an air-safety consulting firm.

“It would have been very scary,” he said. But the strength of air flowing out of the cabin wouldn’t necessarily be powerful enough to pull someone through the door, according to Cox.

Anthony Brickhouse, a professor of aerospace safety at Embry-Riddle Aeronautical University, said if someone had been sitting near the opening without a fastened seat belt, there could have been a tragedy. “We could be looking at a totally different story,” he said.

Had the section ripped away at a higher altitude, risks would have been greater in other ways. The incoming air would have been significantly colder, causing intense discomfort for everyone on board and possibly disorienting them. Also, at cruising heights, passengers may have been walking or not buckled into their seats.

Depressurization incidents like the Alaska flight experienced are rare, but aircraft are designed to withstand them and continue flying. Pilots are trained to move to quickly bring planes down when they happen.

Alaska said it had cleared 18 of its 65 MAX 9 jets to resume flying after determining that their plug doors had gone through “in-depth and thorough” inspections during recent heavy maintenance visits. But the airline later said it has now pulled those planes from service to determine what, if any, further maintenance work may be required to comply with the FAA’s order.

United said 33 of the 79 MAX 9 jets in its fleet had already received the necessary inspections, but said it was suspending service on others to complete the work.

Some non-U.S. carriers, including Panama’s Copa Airlines and Mexico’s Aeroméxico, said they were temporarily grounding their MAX 9 jets pending the necessary inspection.

The Boeing 737 MAX 9 plane involved in the incident was certified by the FAA in November. It is a slightly longer and newer version of the more popular MAX-8 model. There are more than 1,000 MAX-8 models in service, according to Cirium.

Fuselage maker Spirit AeroSystems is responsible for installing the emergency door configuration involved in Friday’s incident. Spirit AeroSystems was working with Boeing on Saturday to determine what went wrong.

Two crashes of the smaller 737 MAX-8 variant in 2018 and 2019 grounded the jets around the world for almost two years. The accidents took 346 lives and drew scrutiny from federal regulators and lawmakers.

The Alaska plane involved in Friday’s incident experienced two pressurization issues on Jan. 4, including one in which a warning light led the airline to remove the plane from extended range flights, Jefferies aerospace analyst Sheila Kahyaoglu said in a research note. The light came on again later in the day on another flight. The details were earlier reported by Air Current, an industry publication.

—Benjamin Katz, Micah Maidenberg, Sharon Terlep and Patience Haggin contributed to this article.

Write to Alison Sider at [email protected]