The National Transportation Safety Board (NTSB) has determined that the dramatic in-flight blowout of a mid-exit door (MED) plug on an Alaska Airlines Boeing 737 MAX 9 in January 2024 was caused by Boeing’s failure to provide adequate training, guidance, and oversight to its manufacturing workforce. The NTSB also cited the Federal Aviation Administration (FAA) for ineffective oversight of Boeing’s known and recurring recordkeeping and compliance issues.

On January 5, 2024, Alaska Airlines Flight 1282 was climbing out of Portland, Oregon, when the left mid-exit door plug separated from the aircraft at 14,830 feet, resulting in rapid decompression. The force of the blowout sucked some passengers’ belongings out of the cabin, dropped oxygen masks, and swung open the cockpit door, injuring a flight attendant. Seven passengers also suffered minor injuries. The two pilots, three other flight attendants, and 164 passengers were unharmed. The flight returned safely to Portland.

The missing door plug was found in a Portland neighborhood two days later. Investigators discovered that the four bolts required to secure the plug were missing before the accident. The unsecured plug had gradually shifted upward during previous flights until it finally detached during the accident flight.

Key Findings

• The NTSB found that the bolts securing the MED plug were never reinstalled after being removed at Boeing’s Renton, Washington, factory during manufacturing to allow for rivet repair work. Required documentation and quality assurance inspections were not completed, in violation of Boeing’s own procedures.
• Specialized technicians, who are supposed to handle MED plug work, were not present when the plug was closed. No one involved could recall who had performed the work, and no removal record was generated, bypassing critical safety and inspection steps.
• The FAA failed to identify or address Boeing’s long-standing nonconformance issues, despite a documented history of compliance problems with the company’s parts removal process.
• Boeing’s safety management system (SMS) was found to be immature and lacking formal FAA oversight at the time, failing to proactively identify or mitigate risks.
• The investigation also highlighted the need for better flight crew training on oxygen mask use and for increased use of child restraint systems for passengers under two years old.

The NTSB concluded that the root cause was Boeing’s inadequate training, guidance, and oversight, which led to the failure to reinstall the securing bolts and the lack of proper documentation and inspection. The FAA’s ineffective oversight and failure to enforce corrective actions contributed to the accident.

Safety Recommendations

The NTSB issued several new recommendations to both the FAA and Boeing, including:

• Requiring the retrofit of all in-service Boeing 737s with a newly certified MED plug design enhancement.
• Improving FAA oversight systems to better track and resolve recurring manufacturing discrepancies.
• Mandating structured, documented training and clearer guidance for Boeing manufacturing personnel.
• Convening an independent third-party review of Boeing’s safety culture.
• Enhancing flight crew training for emergency oxygen systems and revising standards for portable oxygen bottles2.

Previously issued recommendations regarding cockpit voice recorders and child restraint systems were reiterated to the FAA and airline associations,