A United Airlines Boeing 737 MAX 8 flying from Seattle to Newark turned towards Chicago and descended over the US Midwest on Tuesday 13 October, then climbed back to cruise altitude and completed the flight to Newark. According to aviation news site AirLive, which based its report on flight deck communications, an elderly passenger was trapped in the aft lavatory at the time because the door mechanism had failed1. United has not publicly confirmed the event. The flight profile itself is established: open ADS-B data from adsb.lol show the turn, the descent and the climb2.

What the flight data show

The flight was UA1900, operated by Boeing 737-8 N27274, a 2022 aircraft registered to United Airlines according to the FAA registry32. It took off at 14:05 UTC (07:05 local time in Seattle) and cruised east at FL3502. At about 16:40 UTC, over Minnesota and roughly two and a half hours after departure, it turned from an easterly track to the south-east, towards Chicago. The descent began at 16:51. At 17:00 UTC, over Wisconsin and about 115 nautical miles from Chicago O'Hare, the aircraft reached its lowest point at FL2702.

The 737 then turned back east and climbed. By 17:12 UTC it was level at FL370 and heading for New Jersey. UA1900 landed at Newark at 18:33 UTC, almost four and a half hours after takeoff. The ADS-B data show no emergency transponder code during this period2.

What AirLive reports about the passenger

According to AirLive, citing flight deck communications, the crew discovered about two and a half hours into the flight that a 69-year-old woman was locked in the aft lavatory. Flight attendants tried to open the door from the outside using standard procedures, but the latch stayed stuck. After 15 minutes of attempts, including the use of onboard tools, the door was still closed1.

The captain then informed air traffic control. According to AirLive, he was not willing to leave her locked in for more than 20 minutes and prepared a diversion to Chicago O'Hare. During the descent the flight attendants managed to free her. With the passenger safe and unharmed, the crew cancelled the landing in Chicago and continued to Newark, where medical staff met her at the gate; she was reported to be in stable condition1. We have not found a statement from United.

How a lavatory door opens from the outside

Getting trapped is exactly what certification rules are meant to prevent. Under US rule 14 CFR 25.820, all lavatory doors must be designed so that nobody can become trapped inside, and any locking mechanism must be capable of being unlocked from the outside without special tools4. EASA certification specification CS 25.820 uses the same wording5.

How that works in practice varies by aircraft type. On many aircraft the release is hidden under the metal lavatory sign on the door: flip the sign up and the lock can be slid open6. Cabin crew use it only when needed, for example when someone is unwell or locked in6. We covered a similar case earlier this month, when a passenger was stuck in an American Airlines lavatory. An outside unlock does not help, however, when the door mechanism itself jams, and according to AirLive that is what happened here1.

What cabin crew do when the door will not open

If the door stays shut, cabin crew stay in contact with the passenger and inform the flight deck, as AirLive reports happened on UA19001. On an Indian SpiceJet flight from Mumbai to Bengaluru in January 2024, a passenger was stuck in the lavatory for more than an hour. The crew tried to open the door several times and then slid a note inside: do not panic, close the toilet lid, sit on it and secure yourself for landing. After arrival an engineer opened the door and the passenger received medical support, SpiceJet told the BBC11.

It is not the first time at United either. In September 2019, flight 1554 from Washington to San Francisco diverted to Denver because, according to United, the lavatory door had become inoperative with a passenger inside. She was freed after landing and was unhurt, the airline told the BBC12.

An occupied lavatory, landing and the seat belt sign

A passenger who cannot leave the lavatory is also a problem for the landing itself. US airline rules require each person aged two or older to occupy an approved seat with the safety belt fastened during movement on the surface, takeoff and landing7. The Fasten Seat Belt sign must be on during taxi, for each takeoff and landing and at any other time the pilot in command considers necessary, and passengers must keep their belts fastened while it is lit8. Under EASA rule CAT.OP.MPA.225 the commander must be satisfied, before takeoff and landing, during taxi and whenever safety requires it, that each passenger occupies a seat or berth with the belt properly secured9.

Someone who is locked in cannot comply. The SpiceJet note shows how a crew then tries to get the passenger through the landing as safely as possible11.

The captain's decision

Under US rules the pilot in command is directly responsible for, and the final authority on, the operation of the aircraft10. On UA1900, according to AirLive, the passenger's wellbeing weighed heavily: after 15 minutes of failed attempts the captain began the diversion, with a 20-minute limit1. Once the door opened during the descent and the passenger was unhurt, there was no longer a reason to land in Chicago1. The ADS-B data show the aircraft back at cruise altitude within 12 minutes of its lowest point, continuing to Newark2.