Date: 5th January 2024
Aircraft: 737-9 MAX, Registration: N704AL
Flight: AS1282
Departure Airport: Portland (PDX)
Arrival Airport: Ontario, CA (ONT)
Airport Diverted to: Portland (PDX)
Departure Time: 17:06 (local time)
Arrival Time: 17:26 (local time), reached the gate at 17:30
Image of an aircraft.
I do not think this is the one involved in the incident.
On 5th January 2024, an Alaska Airlines flight from Portland to Ontario, CA, experienced a mid-cabin exit door plug separating from the aircraft while in flight. The in-flight departure of the mid-cabin door plug resulted in the rapid decompression of the aeroplane. In this post, I take a look at what happened and some of the consequences of this event.
Alaska Airlines flight AS1282 departed PDX at 17:06 local time. The flight to Ontario was operated by a 737-9 MAX aircraft that was delivered new from Boeing on 31st October 2023. According to Flightradar24 data, it reached a maximum altitude of 16,325 feet before diverting back to PDX after the mid-cabin exit door separated from the aircraft mid-flight. The flight was carrying 171 passengers and 6 crew but no injuries were reported. Remarkably, the seat beside the mid-exit door plug was empty with many speculating that if a person had been sitting there, they would have been sucked out of the aircraft.
What is a mid-cabin door plug?
Aircraft have strict regulations about seating capacity and emergency exits and passengers must be able to evacuate the aircraft within 90 seconds using half of the available emergency exits. Therefore, in dense seating configurations of the 737-9 MAX, there is a mid-cabin exit door aft of the wings, before the rear cabin doors in order to meet these evacuation requirements. However, the door can be deactivated if the cabin does not have a denser seating configuration. On the Alaska Airlines aircraft involved in this incident, the extra exit door was not needed as the high-density seating configuration was not used. The extra door was not activated and permanently 'plugged'. From the inside, it would be impossible to tell if there was a door plug present as the door plug looks just like the interior wall panel in the rest of the aircraft.
Aftermath
As a result of this incident, many airlines grounded their 737-9 MAX aircraft in order for inspections to take place.
On 6th January, the FAA issued an Emergency Airworthiness Directive requiring inspections of all 737-9 aircraft with a mid-cabin exit door plug.
On 11 January, the FAA opened a formal investigation into Boeing to
"determine if Boeing failed to ensure completed products conformed to is approved design and were in a condition for safe operation in compliance with FAA regulations"
On 6th February the NTSB released the preliminary report on AS1282. It states that:
"the four bolts that prevent upward movement of the MED plug were missing before the MED plug moved upwards off the stop pads."
[MED Plug = Mid exit door plug]
It is almost certain that these missing bolts were the reason for the mid-flight departure of the MED plug. However, it has been noted that the aircraft involved in the incident had suffered several pressurisation warnings before the accident and as a result, the aircraft was prevented from flying over large bodies of water in case a diversion became necessary.
The recent incident has raised questions about the safety of Boeing aircraft, especially after the crashes of the Boeing 737 MAX aircraft a few years ago and whether Boeing is cutting corners to increase profits over safety. However, many Boeing aircraft fly every day and operate safely so we cannot judge the safety of a company or aircraft from the outcome of one incident.
What do you think about this incident and the latest developments following this event?
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