The rapid descent of a Tui Airways plane could be linked to its pilots being grounded for long periods during the coronavirus pandemic, investigators said.
Sixty-seven passengers and six crew were on board the flight when it was involved in a “serious incident” as it approached Aberdeen Airport on September 11.
The Air Accidents Investigation Branch (AAIB) said the pilots were instructed by air traffic control (ATC) to abort the landing 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 “deviated significantly from the expected flight path” by descending to as low as 1,780 ft at a speed more than 40% quicker than the one selected by the pilots.
This was a “high rate of descent” and an increase in speed which was “not corrected in a timely manner”, the AAIB said.
An investigation into the cause of the incident 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.
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
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Air travel has been decimated by the coronavirus pandemic, with flight numbers heavily reduced.
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.”
A Civil Aviation Authority spokesman said: “Safety is our first priority, and we continue to offer every assistance to the AAIB in its investigation of the incident.
“We will take any action necessary to maintain the UK’s excellent aviation safety record.
“While the AAIB has not confirmed a link between this incident and pilots’ general lack of operational flying due to Covid, it is an issue that CAA and airlines have been aware of and acted on.”
Martin Chalk, general secretary of the pilots’ union Balpa, said many airlines had given pilots extra time to prepare for their return to flying, but “there have also been commercial pressures which act in the opposite direction”.
It called on the Government to provide funding for airlines to “provide extra training and experience to avoid any degradation of aviation’s enviable safety standards”.
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