Security guards at Heathrow Airport will launch a three-day strike on Thursday in a dispute over pay.
Members of Unite have already held 15 days of industrial action, including over the busy Easter period.
Heathrow said it has contingency plans in place to keep the airport open and operating as usual, adding that passengers can expect to have a “smooth” half-term getaway.
Heathrow chief executive John Holland-Kaye said: “Passengers should not be concerned about strike action by Unite over the half-term getaway.
“The 15 days of strike action over the Easter peak and coronation weekends have had no impact on the smooth running of the airport, and passengers have not noticed any difference from the normal great service they expect at Heathrow.
“These strikes are completely unnecessary. When I speak to colleagues the overwhelming message is that they just want to vote on our pay offer, but Unite won’t let them.
“We made a generous 10% offer early on, to make sure colleagues got a substantial increase when they needed it most. Unite’s delays mean non-union colleagues, as well as the majority of colleagues who are union members, who voted to accept our previous offer are losing out.”
May half-term is always a very busy time for travel, and Heathrow said it may take a little longer than usual to get through security, but added this will be “well-managed and kept flowing”.
Unite said Heathrow security officers are paid less than workers at other major airports in London and the South East.
Regional co-ordinating officer Wayne King said: “There is absolutely no justification for security officers at Heathrow being paid far less than comparable officers at other London airports.
“Heathrow regularly trumpets how successful it is as the UK’s premium airport so there is no defence in it paying bargain basement wages.
“Heathrow can clearly meet a cost-of-living increase for our members; they’re deliberately choosing not to, pushing our members deeper into financial difficulties.”
Rory Boland, Editor of Which? Travel, said: “While it is positive to see Heathrow has put contingency plans in place to minimise disruption during the forthcoming strike action, those with flights booked over half term will no doubt still have concerns that their trips could be impacted.
“It’s essential that airlines and airports work together to keep travellers updated during this period of industrial action, and fulfil their legal obligations to passengers in the event of cancellations or delays.
“Travellers should also ensure they have travel insurance from the date they book their trip and always check the policy carefully, to ensure it covers all the eventualities you would expect – in particular, not all policies will cover travellers in the event of strikes by airline or airport staff, for example.”