Alaska Airlines Flight 1282, 2024: A Door Plug and a Parts-Removal Process
The NTSB found that a door plug separated in flight because the bolts securing it were not reinstalled after manufacturing rework, and that training, guidance, oversight and regulatory surveillance all fell short.
Aerospace & Space · Last reviewed
What happened
On January 5, 2024, a Boeing 737-9 operated by Alaska Airlines as flight 1282 lost its left mid exit door plug in flight and depressurized rapidly while climbing through about 14,830 ft after takeoff from Portland, Oregon. The crew carried out the emergency procedures and returned to Portland for a safe landing. One flight attendant and seven passengers received minor injuries. The airplane had a hole in the fuselage where the plug, a rectangular structure about 29 inches wide and 59 inches high, had been installed. Four bolts that would secure the plug from moving upward were not found.
What the NTSB found
- Probable cause: the in-flight separation of the plug, due to Boeing's failure to provide adequate training, guidance and oversight needed to ensure that manufacturing personnel could consistently and correctly follow its parts-removal process. That process was meant to document and ensure that securing bolts and hardware removed for rework were properly reinstalled.
- Contributing: the FAA's ineffective compliance-enforcement surveillance and audit-planning activities, which failed to identify and ensure that Boeing addressed repetitive and systemic nonconformance issues with the parts-removal process.
- The NTSB issued 19 new safety recommendations as a result of the investigation.
Apply the lesson
- In your own work, when a part or fastener is removed for rework, what record shows that it was put back, and who checks the record?
- If the same nonconformance has appeared several times, who sees the pattern? A single report may look minor while a count of them does not.
- Review whether the process depends on every person remembering a step, or whether the documentation makes a missed step visible.
Engineering lesson: a safety-critical step that depends on memory will eventually be missed. The process has to record it and make a gap visible, and oversight has to look at patterns, not single events.
What the NTSB recommended
The NTSB issued 19 new safety recommendations. Its recommendations to the FAA, as listed on its investigation page, include:
- Once certification of Boeing's design enhancement for ensuring the complete closure of 737 mid exit door plugs is complete, issue an airworthiness directive requiring that all in-service plug-equipped airplanes be retrofitted with it (A-25-15).
- Revise the compliance enforcement surveillance system so that inspectors can effectively identify, record, track and resolve recurring and systemic discrepancies and nonconformance issues, including those tied to specific manufacturing processes (A-25-16).
- Revise the audit planning activities so that they provide the same ability to identify, record, track and resolve recurring and systemic nonconformance issues (A-25-17).
- Revise the records systems so that they provide the records needed for that oversight (A-25-18).
Related tools and labs
Calculators, labs and simulators are part of the All-Access Pass.
More case studies
- Mars Climate Orbiter: When Units Become an Interface Failure
- Space Shuttle Challenger, 1986: A Joint Seal and a Launch Decision
- Space Shuttle Columbia, 2003: A Foam Strike and Organizational Causes
- Tacoma Narrows Bridge, 1940: Wind and a Slender Deck
- Hyatt Regency Kansas City Walkways, 1981: A Connection Detail Changed During Construction
- BP Texas City Refinery, 2005: A Tower Overfilled and Trailers in the Wrong Place
- Imperial Sugar Refinery, 2008: A Dust Explosion Fueled by Accumulations
Questions
Was anyone seriously hurt?
The NTSB reports that one flight attendant and seven passengers had minor injuries, and the other occupants were uninjured.
Where is the official report?
The NTSB investigation page, linked below, has the findings and the recommendations.
How many recommendations did the NTSB issue?
Nineteen new safety recommendations, including several to the FAA about surveillance, audit planning and records for production oversight.
What was the physical cause?
The NTSB found that the plug separated in flight because the securing bolts and hardware removed for rework were not properly reinstalled. The page says four bolts that secure the plug against upward movement were not found.
Sources
Educational material. Examples use simplified, hypothetical inputs and are not a design, a construction document or professional engineering advice. Confirm requirements with the codes and standards adopted where the work is built and with a licensed engineer.