The Boeing 737 MAX series has come under fire again, but this time, it is limited to one variant, the Boeing 737 MAX 9. This comes after an Alaska Air 737 MAX 9’s rear mid-cabin exit door plug separated from the fuselage of the aircraft as the plane reached FL160. As such, the FAA has issued a directive grounding all Boeing 737 MAX 9 variants with the same configuration as that of the Alaska Airlines 737 MAX 9, the one equipped with the rear mid-cabin door plug.
The Role of the Rear Mid-Cabin Exit Door
The primary purpose of the rear mid-cabin exit door on the 737-9 MAX is to meet stringent evacuation requirements set by aviation authorities. In scenarios where aircraft are configured with a high-density seating arrangement, these additional exits are crucial. They ensure that in the event of an emergency, passengers can evacuate the aircraft within the mandated 90 seconds, even if half of the exits are blocked.
Interestingly, not all carriers operating the 737 MAX 9 utilize this additional exit. For instance, Alaska Airlines and United Airlines have chosen configurations for their 737 MAX 9 fleets that include fewer than 180 seats. This seating arrangement falls within the safety guidelines that negate the need for the extra mid-cabin exits. As a result, these airlines opt for a “plugged” version of the aircraft.
The “plug” system comes into play in aircraft where the additional mid-cabin exits are not required. It essentially involves sealing off these exits to maintain the aircraft’s structural integrity and aerodynamic efficiency. The plug is a permanent fixture on these aircraft, ensuring that the unused door does not impact the plane’s performance.
Despite being a non-functional part of these aircraft, the area around the door plug is subject to rigorous safety inspections. The Federal Aviation Administration mandates these checks to ensure that the plug does not compromise the aircraft’s safety in any way. This is particularly crucial given recent scrutiny over the 737 MAX series.
Airlines that Operate the 737 MAX 9
This table provides a clear overview of the different airlines operating the Boeing 737-9 MAX, the number of such aircraft in their fleet, and the status of the mid-cabin exit door plugs for each.
| Airline | Aircraft Model | Number of Aircraft | Mid-Cabin Exit Door Plug Status |
|---|---|---|---|
| Aeromexico | 737-9 MAX | 19 | All with mid-cabin exit door plugs |
| Air Tanzania | 737-9 MAX | 1 | No mid-cabin exit door plug |
| Alaska Airlines | 737-9 MAX N704AL | 65 | All with mid-cabin exit door plugs |
| Copa Airlines | 737-9 MAX | 29 | 21 with plugs, 8 without (HP-9901CMP to HP-9908CMP) |
| Corendon Dutch Airlines | 737-9 MAX | 2 | None with mid-cabin exit door plugs |
| flydubai | 737-9 MAX | 3 | None with mid-cabin exit door plugs |
| Icelandair | 737-9 MAX | 3 | None with mid-cabin exit door plugs |
| Lion Air | 737-9 MAX | 3 | None with mid-cabin exit door plugs |
| SCAT Airlines | 737-9 MAX | 5 | None with mid-cabin exit door plugs |
| Turkish Airlines | 737-9 MAX | 5 | All with mid-cabin exit door plugs |
| United Airlines | 737-9 MAX | 79 | All with mid-cabin exit door plugs |
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