Heathrow insists it has contingency plans in place to combat a strike by security staff for ten days including Easter.
The Unite union warned of “severe delays and disruption” as more than 1,400 security guards voted to walk out in a dispute over pay.
The action is planned to take place at Terminal 5, exclusively used by British Airways, from March 31 until Easter Sunday, April 9.
The dispute is over a 10% pay rise offered to workers, which the union described as a real terms pay cut with the real rate of inflation standing at 13.4%, following a period of pay freezes and cuts.
Unite regional co-ordinating officer Wayne King said: “Strike action will cause huge disruption and delays at Heathrow throughout Easter but this dispute is entirely of HAL’s [Heathrow Airport Ltd] own making it has had every opportunity to make a fair pay offer but has failed to do so.”
However, a Heathrow spokesperson said: “Passengers can be reassured that we have contingency plans which will keep the airport open and operational despite unnecessary threats of strike action by Unite.
“We have proposed an inflation beating 10% increase in pay which the public will recognise is fair and a majority of our colleagues have told Unite is not worth striking over.
“We urge Unite to come back to the table to discuss implementing it.
“Threatening to ruin people’s hard-earned holidays with strike action will not improve the deal.
“We want to do the right thing by our people and our passengers, each day only delays this pay rise reaching Unite members’ pockets.”
Security officers would see starting salaries rise to £27,754 plus shift pay and allowances if the 10% increase is accepted. It follows a 4% increase and a £2,000 lump sum cost of living payment last year.