What to Know About the Alaska Airlines 737 Max 9 Jet That Suffered a Blowout

NEW YORK—An emergency landing by an Alaska Airlines jetliner has prompted U. S. federal authorities to ground some Boeing 737 Max 9 aircraft, adding another episode to the troubled history of Boeing’s Max lineup of jets.

The NTSB has begun an investigation that is likely to last months and focus on the paneled-over exit door that blew off. The so-called door plug is installed on some jets with fewer seats instead of an emergency exit panel. The jets ordered grounded by the FAA all have those panels installed.

United Airlines, the world’s biggest operator of Max 9s, has grounded its entire fleet of 79 Max 9s. Alaska and United are the only two U. S.

passenger airlines that operate Max 9 aircraft. The companies operate nearly two-thirds of the 215 Max 9 aircraft in service around the world, according to aviation analytics firm Cirium. Six other airlines use the Max 9: Panama’s Copa Airlines, Aeromexico, Turkish airlines, Icelandair, flydubai, and SCAT Airlines in Kazakhstan, according to Cirium.

Copa said it had temporarily suspended 21 Boeing 737 Max 9s to comply with the FAA’s order. Alaska Airlines had canceled 163 flights on Sunday, or 21% of its schedule, according to Flightaware. United Airlines had canceled 247, about 9% of its scheduled flights.

Not all of the cancelations were necessarily due to the Max 9 crisis. Alaska Airlines said the groundings had resulted in at least 160 flight cancelations by Saturday evening and disruptions will last through at least mid-week. United had said Saturday evening said the inspections will result in about 60 cancelations.

After arriving in Portland to investigate the Alaska Airlines incident, the NTSB’s Homendy said the U. S. has “the safest aviation system in the world.

” However, a surge in close calls between planes at U. S. airports in the past year prompted the FAA to convene a “safety summit” last year, in which officials encouraged airlines and pilots to redouble their attention to careful flying.

The incident has also renewed questions about the safety of Boeing’s Max aircraft, which the newest version of the company’s storied 737. There are two versions of the aircraft in service: the Max 8 and the Max 9, which is the larger of the two. Regulators around the world grounded Max 8 planes for nearly two years after a Lion Air flight crashed in Indonesia in 2018, and an Ethiopian Airlines Max 8 crashed in 2019.

Boeing changed an automated flight control system implicated in the crashes. Last year, the FAA told pilots to limit use of an anti-ice system on the Max in dry conditions because of concern that inlets around the engines could overheat and break away, possibly striking the plane. And in December, Boeing told airlines to inspect the planes for a possible loose bolt in the rudder-control system.

However, those past issues are unrelated to Friday’s blowout, which is exceedingly rare in air travel, according to Anthony Brickhouse, a professor of aerospace safety at Embry-Riddle Aeronautical University. Brickhouse said fuselage panels sometimes tears off planes but he could not recall a previous incident that blew a gaping hole like the one that forced Friday’s emergency landing. .