Len McCluskey, general secretary of the UK trade union Unite, claimed the airline has published a timetable to “fire and rehire” thousands of workers on August 7th.
In a letter to British Airways chief executive Alex Cruz, Mr McCluskey pledged to “work every hour between now and then to convince you not to do so”.
Take this as an intention to defend our members by moving towards industrial action with immediate effect
British Airways owner IAG announced in April that it would cut up to 12,000 jobs due to the reduction in flights caused by the coronavirus pandemic.
Unite has claimed the company is planning to rehire remaining employees on downgraded terms and conditions if an agreement cannot be reached.
Mr McCluskey wrote: “Your decision to adopt a scorched earth strategy with a fire and rehire approach was always despicable.
“You and your management team have dragged the good name of British Airways through the mud.
“Have you ever asked yourself why so many MPs from all parties, at the highest level, have condemned British Airways or why newspaper and media outlets have been appalled at your actions?
“Perhaps you don’t understand that the British sense of fair play runs deep in the psyche of the British people.”
He added: “Take this as an intention to defend our members by moving towards industrial action with immediate effect.”
Unite represents thousands of British Airways staff including cabin crew and engineers.
British Airways said in a statement the pandemic has resulted in job losses across every industry and many airlines have “already made thousands of staff redundant”.
It continued: “We are not immune to this crisis. We have to adapt to survive, so we will continue with the proper, lawful consultative process and we will keep inviting union representatives to discuss our proposals to the serious challenges we face.
“It is not too late to find solutions – as we have done with (pilots’ union) Balpa – and to protect jobs.”
Balpa last week urged its members employed by the carrier to accept a package including pay cuts and job losses in a bid to avoid more redundancies.
The proposed deal includes voluntary part-time working, voluntary severance, voluntary external secondments, and a holding pool of the equivalent of 300 pilots employed on reduced pay ready to return to flying as demand picks up.
The number of flights British Airways operated during the first two weeks of July was down 85% compared with the same period in 2019.
The International Air Transport Association released an updated forecast on Tuesday showing that the global recovery in air travel has been slower than expected.
Demand is not expected to return to pre-pandemic levels until 2024, one year later than previously projected.