The heroic actions of the crew of Alaska Airlines Flight 1282 ensured everyone survived last year when a door plug panel flew off the plane shortly after takeoff from Portland, leaving a gaping hole that sucked objects out of the cabin, National Transportation Safety Board Chair Jennifer Homendy said June 24.

But, Homendy said, “the crew shouldn’t have had to be heroes, because this accident never should have happened.”

The board found that lapses in Boeing’s manufacturing and safety oversight, combined with ineffective inspections and audits by the Federal Aviation Administration, led to the terrifying malfunction.

The NTSB investigation over the past 17 months found that four bolts securing a door plug panel were removed and never replaced during a repair as the Boeing 737 Max 9 aircraft was being assembled.

Boeing and Spirit AeroSystems — the company that made and installed the door plug — are redesigning them with another backup system to keep the panels in place even if the bolts are missing, but that improvement isn’t likely to be certified by the FAA until 2026 at the soonest. The NTSB urged the companies and the regulator to make sure every 737 Max is retrofitted with those new panels.

And the NTSB found bigger problems. “An accident like this only happens when there are multiple system failures,” Homendy said.

Both Boeing and the FAA have improved training and processes since the incident, according to the NTSB, but board officials said the company and agency need to better identify manufacturing risks to make sure such flaws never sneak through again.

Homendy did single out Boeing’s new CEO, Kelly Ortberg, for improving safety since he took over last summer, though she said more needs to be done.

The NTSB recommended that Boeing continue improving its training and safety standards and make sure everyone knows when actions must be documented. Board members also highlighted the need to ensure that everyone throughout the company understands its safety plan as well as executives do.

The board also urged the FAA to step up and make sure its audits and inspections address key areas based on past problems and systemic issues.

Many of the NTSB recommendations echo a report the Transportation Department’s Inspector General issued last year and that the FAA is already working to implement.

The blowout aboard Alaska Airlines Flight 1282 occurred minutes after it took off from Portland and created a roaring air vacuum that sucked objects out of the cabin. Seven passengers and one flight attendant sustained minor injuries, but no one was killed. Pilots were able to land the plane safely back at the airport.

The accident occurred as the plane flew at 16,000 feet. Oxygen masks dropped during the rapid decompression and a few cellphones and other objects were swept through the hole in the plane as 171 passengers contended with wind and roaring noise.

The first six minutes of the flight to Southern California’s Ontario International Airport were routine. The plane was about halfway to its cruising altitude and traveling at more than 400 mph when passengers described a loud “boom” and wind so strong it ripped the shirt off someone’s back.

The 2-foot-by-4-foot piece of fuselage covering an unused emergency exit behind the left wing had blown out. Only seven seats on the flight were unoccupied, including the two seats closest to the opening.

NTSB member J. Todd Inman said the Alaska Airlines accident would have been worse if it had happened over the ocean and far from land, but the carrier had already restricted the plane used for Flight 1282 to overland flights because of an unresolved maintenance issue with a fuel pump. The airline took that step on its own, going above FAA requirements, Inman said.

The panel that blew off had been removed at a Boeing factory so workers could repair five damaged rivets, but bolts that help secure the door plug were not replaced. It’s not clear who removed the panel.

The NTSB said in a preliminary report that four bolts were not replaced after the repair job but the work was not documented.

Investigators determined the door plug was gradually moving upward over the 154 flights before the incident before it ultimately flew off.

Boeing factory workers told NTSB investigators they felt pressured to work too fast and were asked to perform jobs they weren’t qualified for, including opening and closing the door plug on the particular plane involved. None of the 24 people on the door team was ever trained to remove a door plug and only one of them had ever removed one before. That person was on vacation when it was done on the plane at issue.

Investigators said Boeing did not do enough to train newer workers who didn’t have a background in manufacturing. Many who were hired after the pandemic lacked that experience, and there weren’t clear standards for on-the-job training.

Regulators at the Federal Aviation Administration have capped Boeing’s 737 Max production at 38 jets a month while investigators ensure the company has strengthened its safety practices.

Associated Press writer Claire Rush in Portland contributed to this report.