British Airways check-in and ground staff at Heathrow have voted overwhelmingly in favour of going on strike, causing more misery for holidaymakers already facing a summer of travel chaos.
Members of the GMB and Unite unions have backed possible strike action later this year in a ballot which closed earlier on Thursday.
GMB members voted by 91% in favour of industrial action while Unite said 94% of its members backed action.
The move threatens to bring more disruption to travellers who have suffered months of delays at airports and flight cancellations due to staff shortages.
The boss of Heathrow has already warned that passengers could face another 18 months of travel disruptions as the aviation sector struggles to fully recover capacity after it cut tens of thousands of jobs during the pandemic.
Both the GMB and Unite unions say the Heathrow strikes are over a 10 per cent cut in pay imposed on staff during the pandemic, which they say has not been reinstated.
BA say they have offered staff a 10 per cent “payment”. But union chiefs say the offer is a one-off and want the full salary returned.
In total, more than 700 BA check-in staff and ground handling agents could strike during the industrial action.
After the ballot result was announced, the GMB said: “Industrial action dates will be confirmed in the coming days but are likely to be during the peak summer holiday period.”
Nadine Houghton, GMB national officer, said: "With grim predictability, holidaymakers face massive disruption thanks to the pig-headedness of British Airways.
"BA have tried to offer our members crumbs from the table in the form of a 10% one-off bonus payment, but this doesn't cut the mustard.
"Our members need to be reinstated the 10% they had stolen from them last year with full back pay and the 10% bonus which other colleagues have been paid.
"GMB members at Heathrow have suffered untold abuse as they deal with the travel chaos caused by staff shortages and IT failures.
"At the same time, they've had their pay slashed during BA's callous fire and rehire policy.
"What did BA think was going to happen?
"It's not too late to save the summer holidays - other BA workers have had their pay cuts reversed.
"Do the same for ground and check-in staff and this industrial action can be nipped in the bud."
Speaking earlier on Thursday, Ms Houghton, said industrial action could hit the school holidays.
She told BBC Radio 4’s Today programme: “Look, we still need to meet with the strike committee, we need to review where we are in terms of dates but yes absolutely, this could impact on the summer holidays, but the blame for this must be squarely put at the door of BA.”
Unite officer Russ Ball said: "The problems British Airways is facing are entirely of its own making. It brutally cut jobs and pay during the pandemic even though the Government was paying them to save jobs.
"In the case of this dispute, they have insulted this workforce, slashing pay by 10% only to restore it to managers but not to our members.
"BA is treating its loyal workforce as second class citizens and they will not put up with it a moment longer.
"Strike action will inevitably cause severe disruption to BA's services at Heathrow.
"The company has a short window of opportunity to reinstate our members' pay before strikes are called. I urge BA not to squander that opportunity."
British Airways said it was “extremely disappointed” that staff at Heathrow had voted to strike over pay.
“We’re extremely disappointed with the result and that the unions have chosen to take this course of action,” a spokesperson said in a statement.
“We are fully committed to work together to find a solution, because to deliver for our customers and rebuild our business we have to work as a team.”
Downing Street said strike action by British Airways workers would only add to the “misery” passengers are suffering at airports.
A No 10 spokesman said: "This is obviously a matter for British Airways and the unions and we would strongly encourage both to come together to find a settlement.
"We don't want to see any further disruption for passengers and strike action would only add to the misery being faced by passengers at airports.
"DfT (Department for Transport) will obviously work closely to look at what contingency measures BA could put in place and we expect BA to put in place contingency measures to ensure that as little disruption is caused, and that where there is disruption that passengers can be refunded".