NTSB: Boeing’s oversight failures caused MAX 9 door plug blowout; FAA also criticised

The NTSB has determined that Boeing’s inadequate training, oversight, and documentation practices led to the mid-exit door (MED) plug blowout on an Alaska Airlines 737 MAX 9 flight in January 2024. The plug, which blew off at 14,830 feet, was found to have been improperly reinstalled without the required bolts after factory repairs months earlier.

The investigation revealed that the plug was opened without documentation and closed by unauthorised personnel, bypassing mandatory inspections. Boeing’s safety management system (SMS) was found to be ineffective, and the FAA was faulted for failing to address Boeing’s known systemic issues.

NTSB Chair Jennifer Homendy said the accident was “preventable” and underscored broader risks from Boeing’s recurring quality lapses. Seven passengers and a flight attendant sustained minor injuries due to the rapid depressurisation, and passenger belongings were blown out of the cabin.

The NTSB issued new safety recommendations to both Boeing and the FAA and reiterated earlier warnings to aviation industry associations. The final report will be published in the coming weeks.