A United Airlines Boeing 777 diverted after an indicator wrongly told its pilots that the cargo door was open.
Sunday’s Flight 1731, from Hawaii’s Kona International Airport, was supposed to land in Denver around 5:30 a.m. local time on Monday.
Three hours into the journey, the plane descended below 10,000 feet as it flew over the Pacific Ocean, according to Flightradar24 data. It landed in San Francisco shortly before 4 a.m. local time, nearly six hours after leaving Hawaii.
The trip to Denver usually takes about six hours, but flying so low requires a slower speed.
The Federal Aviation Administration said in a statement that the pilots reported that an indicator said the cargo door was open.
However, it turned out that the problem was actually with the indicator itself. An airline spokesperson told Business Insider that the plane diverted to “address a malfunctioning door sensor.”
The plane in question is 28 years old, suggesting a maintenance problem. There were 360 passengers and 10 crew members on board.
“We have arranged for a different aircraft to take our customers to Denver Monday morning,” the United spokesperson added. The FAA said it will investigate the incident.
An open door on a plane would be a very dangerous situation, so it makes sense that the pilots were cautious and diverted to the nearest airport.
Descending below 10,000 feet would also make the air on board breathable if the cabin had depressurized due to an opening.
In 1974, a McDonnell Douglas DC-10 operated by Turkish Airlines suffered a fault with a cargo door latch.
This led to an explosive decompression, which cut off critical controls and led to the deaths of all 346 people on board. It remains one of the deadliest aviation disasters in history.
Two years earlier, a cargo door on American Airlines Flight 96 broke off due to a design flaw with the DC-10. The rapid decompression caused the passenger cabin’s floor to collapse, and eleven people were injured.
Advancements in aviation safety and design mean such events are even rarer today.
