Investigators have issued a warning to holidaymakers after a "serious incident" on a Tui flight.
Pilots were instructed by air traffic control (ATC) to abort the landing of the plane, which was travelling from Majorca to Aberdeen, due to a search-and-rescue helicopter in the area.
After climbing close to the altitude of 3,000ft requested by ATC, the Boeing 737 descended to as low as 1,780ft at a speed more than 40% quicker than the one selected by the pilots.
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Sixty-seven passengers and six crew were on board the flight on September 11 - and it took 57 seconds for the crew to increase the altitude and correct the flight path, before safely landing the aircraft.
Air Accidents Investigation Branch (AAIB) said the rapid descent "deviated significantly from the expected flight path" and the increase in speed was "not corrected in a timely manner".
A report has warned the incident could be linked to pilots being grounded for long periods during the Coronavirus pandemic when flight numbers were heavily reduced.
The investigation into the cause of the rapid descent continues but the preliminary report noted the pilots had experienced "significant periods without flying in the preceding 18 months".
It was the first officer's fourth flight in nearly 11 months while the captain had flown 10 flights during the previous month.
The report stated both pilots had completed flight simulator sessions during the virus crisis but warned it can be "difficult in the simulated environment to replicate moments of high crew workload ".
It added: "Regulators have been concerned that pilots returning to the flight deck following extended periods without flying could be at risk of performing below their normal standard during their first few flights.
"Although this investigation has not established a link between this event and a lack of line flying, this special bulletin is published for awareness and because a link is clearly one possibility."
A Tui spokeswoman said: "We have worked closely with the AAIB throughout this investigation and will continue to do so until a final report is published.
"The health and safety of our customers and crew is always our primary concern and we would like to reassure all customers and crew that the safety of the aircraft was assured throughout this flight.
"We provide training that exceeds all regulatory requirements, this includes the additional refresher and recency training completed by all pilots prior to flights being undertaken.
"The industry has faced unique circumstances with the grounding of many planes and crew due to the Covid-19 restrictions."
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