Missing Bolts and Other Failures Caused Plane Panel to Blow Off, N.T.S.B. Says

Investigators for the National Transportation Safety Board said on Tuesday that a single bolt could have averted a terrifying incident last year when a panel blew off an Alaska Airlines Boeing 737 Max 9 airplane midair.

The agency did not determine who removed and failed to replace the four bolts that typically held the door plug — a panel that fills a gap where an emergency exit would be — in place, causing it to rip off Alaska Airlines Flight 1282 midflight. But investigators said that the door plug would not have come loose if just one of the lower bolts, called vertical movement arrestor bolts, had been installed.

The finding was part of a series of failures highlighted in a public hearing held by N.T.S.B. leaders in Washington to review the findings of their 17-month investigation. The agency determined that the door plug likely detached because Boeing had failed to ensure that workers “consistently and correctly” followed its process to remove and reinstall parts.

“Let me be clear: An accident like this does not happen because of an individual, or even a group of individuals,” said Jennifer Homendy, the N.T.S.B. chairwoman, adding, “An accident like this only happens when there are multiple system failures.”

Ms. Homendy credited the crew of Flight 1282 for averting a crash or fatalities when the panel flew off the aircraft shortly after it took off from Portland International Airport in Oregon on Jan. 5, 2024. But she criticized both Boeing and the Federal Aviation Administration for overlooking or ignoring safety deficiencies that “should have been evident.”

The N.T.S.B. issued nearly two dozen safety recommendations to improve Boeing’s safety procedures and the F.A.A.’s oversight of Boeing and other companies to avoid similar episodes in the future.