A United Airlines flight had to make an emergency landing in Lagos, Nigeria due to a midair incident causing loss of pressure and sharp descents.

It is unclear what caused the jolt; United Airlines has said the cause was not severe turbulence, and that it is “working with aviation authorities in the US and Nigeria to understand the cause.”

A United Airlines jet was forced to make an emergency landing after plummeting mid-air following take-off. At least six people were injured after the plane jolted during the flight from Nigeria on Friday. The flight, which was heading from Lagos to Washington DC, had 245 passengers and 11 crew on board at the time.

Just minutes into a flight, a 52-year-old woman forced an emergency landing because of excruciating pain in her eye, German doctors said. It was thanks to changing air pressure.

A United Airlines flight bound for Puerto Rico made an emergency landing at Newark Liberty International Airport on Saturday morning, according to the FAA. The flight returned to Newark around 10 a.m.

A United Airlines flight from Africa to Washington D.C. had to turn around on Thursday after a "technical issue" caused "unexpected aircraft movement," the airline said.