EasyJet has announced that it has begun consultations on plans to close bases in Stansted, Southend and Newcastle.
It follows an announcement by the airline that it may need to reduce staff numbers by as much as a third due to the coronavirus pandemic.
EasyJet said airports would continue to be part of its route network.
Separately, the Balpa pilots union said EasyJet had told it that 727 of its UK-based pilots were at risk of being fired.
That is equivalent to one in three of its pilots, Balpa said.
EasyJet CEO Johan Lundgren said: “The lower demand environment means we need fewer planes and fewer job opportunities for our people.
“We are committed to working constructively with our employee representatives across the network with the goal of minimizing job loss as much as possible.”
Balpa general secretary Brian Stratton said the job cuts were “an excessive overreaction.”
“EasyJet will not find a supply of pilots waiting to return when the recovery takes place in the next two years.”