Passenger plane dropped 1,200 feet in a minute without pilots noticing
The incident has since been declared as "serious".
A plane carrying 67 passengers and six crew members dropped over 360 metres in less than a minute without the pilots noticing.
The incident was highlighted in a report by the UK Air Accidents Investigation Branch and occurred on 11 September 2021 when a Boeing 737 was due to fly into Aberdeen International Airport.
But as the plane was due to land, a search-and-rescue helicopter had to take off, which was prioritised by air traffic control. The plane pilots were told to implement a 'go-around procedure', which is ordered when the landing is delayed at the last minute.
The pilots carried out the move successfully and brought the plane up to 3,000 feet above sea level. But the plane suddenly dropped - plummeting to 1,780 feet above sea level in just 57 seconds.
Air traffic control radioed the pilots to flag the descent, but by this time, they had already started to lift the plane again.
The incident was been declared "serious" by the Air Accident Investigation Branch, which has since changed its procedures as a result.
The crew was found to be "overloaded" with the stress of conducting the go-around procedure, which is only required at a rate of three per 1,000 UK flights. The pilots had also not flown that type of plan for a long time throughout the pandemic.
To top it all off, the plane's ATC radar system failed to flag the descent.
To stop the same mistake from happening again, all pilots were informed about the incident, go-around and autopilot training were improved, and more measures were brought in to support pilots who are going through long periods without flying.