What began as a routine flight between China and Japan turned into a terrifying freefall after a Japan Airlines codeshare plane suffered a pressurisation failure and dropped nearly 26,000 feet (8km) in under 10 minutes.

The Boeing 737, operated by low-cost subsidiary Spring Japan under flight JL8696/IJ004, took off from Shanghai Pudong bound for Tokyo Narita on Monday evening with 191 people on board.

But just before 7pm, passengers suddenly found themselves reaching for oxygen masks as the aircraft plunged from 36,000 feet to just under 10,500.

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“I heard a muffled boom, and the oxygen mask fell off in a few seconds,” PEOPLE reported.

“The stewardess cried and shouted to put on the oxygen mask, saying the plane had a malfunction.”

Another recalled the moment they were jolted awake.

“Suddenly, all the oxygen masks popped open while I was sleeping.”

A third said they were “on the verge of tears,” writing a will mid-air and sending their bank card PINs to family in case the worst happened.

Footage from inside the cabin showed frightened passengers clutching oxygen masks while a flight attendant issued instructions over the intercom.

Authorities said a warning indicated a fault in the aircraft’s pressurisation system, prompting the pilot to declare an emergency and divert to Kansai International Airport in Osaka.

The plane landed safely just before 9pm, with no injuries reported.

Each passenger was reportedly offered 15,000 yen ($159) in compensation and overnight accommodation.

Japan’s Ministry of Land, Infrastructure, Transport and Tourism has launched an investigation into the incident.