NTSB Releases Final Report on Alaska Door Plug Blowout
By Zach Vasile
The National Transportation Safety Board on Thursday released its final report on a midair door plug blowout on an Alaska Airlines flight last year and assigned ultimate responsibility to Boeing for failing to provide adequate training and oversight for its workers.
The report, which largely restated points laid out by NTSB officials at a public meeting in June, found that the left mid exit door plug at the center of the accident was missing four critical installation bolts.
It faulted Boeing’s safety and quality processes for not catching the problem and failing to properly document every person who worked on the door plug and the surrounding fuselage.
The door plug failed about six minutes into an Alaska flight from Portland, Oregon, to Ontario, California, in January 2024.
The aircraft experienced a decompression, which damaged parts of the cabin interior and dropped unsecured items like cellphones, paper, clothing, and children’s toys onto the Portland suburbs below.
The 737 MAX 9 returned to the airport and landed without further incident. One flight attendant and seven passengers received minor injuries, and no one was killed.
The fuselage with the door plug installed was built in Kansas at Spirit AeroSystems and then brought by rail to Boeing’s Renton, Washington, plant for final assembly.
The arrival inspection of the fuselage revealed a number of rivets had been improperly installed, and to make repairs, the door plug had to be removed.
It was during this rework that Boeing failed to ensure implementation of and compliance with its parts removal process, which would ensure that bolts and other hardware that had to be removed were properly reinstalled, the report states.
The manufacturer did not document the individual or individuals who worked on the door plug during the repairs.
NTSB investigators found that if just one of the missing bolts had been installed, the door plug would not have separated from the aircraft as it did.
‘Safety Culture’ Under Scrutiny
During its public hearing last month, the NTSB said Boeing’s system for training technicians on parts removal was somewhat informal and mostly on the job. A lack of experienced workers also played a role, since this made it harder to catch errors and properly train new personnel.
The agency issued a series of recommendations to Boeing. The manufacturer was directed to continue the certification process for a design enhancement for mid exit door plugs, revise its risk assessment process, and develop recurrent training for technicians centering on parts removal.
As part of that training, the company should develop a standard to determine when parts removal is necessary and create a system for documenting removals, the NTSB said.
Separately, the FAA was faulted for “ineffective compliance enforcement,” which failed to identify and correct “repetitive and systemic nonconformance issues associated with [Boeing’s] parts removal process.”
The NTSB recommended that the FAA revise its auditing and compliance enforcement processes, better train inspectors to recognize systemic nonconformance, and extend the period for retaining audit records.
It also suggested the creation of an “independent panel to conduct a comprehensive review” of Boeing’s “safety culture.” The results from that review would then be used to inform the company’s regulatory safety program, the report said.
