EasyJet says it has begun consultations on plans to close bases at Stansted, Southend and Newcastle.
It follows an announcement by the airline that it may need to reduce staff numbers by up to a third because of the coronavirus pandemic.
The Unite union said nearly 1,300 UK crew members faced losing their jobs.
Pilots' union Balpa said it had been told by EasyJet that 727 of its UK-based pilots were also at risk of redundancy.
https://www.bbc.co.uk/news/business-53239256