Unite has warned holidaymakers they face “severe disruption” at Gatwick Airport this month after ground staff announced a new series of strikes.
More than 230 workers, who work for two contracted firms at the London site, will walk out on multiple dates later in August because of a dispute over pay, the union said.
Unite believes 216 flights could be disrupted during the first wave of industrial action, which it claims could affect around 45,000 passengers.
It comes after around 1,000 Gatwick staff at four other companies axed plans to strike this summer after they were offered “significant” pay rises.
Those taking part in the new walkouts include baggage handlers and airplane ground staff who work for Red Handling, which carries out operations for airlines including Norse Atlantic, Norwegian, Delta and TAP Air Portugal.
They plan to strike for four days from Friday 18 August, and a further four days from Friday 25 August – which includes the August bank holiday weekend.
Unite says Red Handling staff earn between £11 and £12 an hour, which it says are among the lowest rates for such roles.
Also taking part are union members employed by Wilson James, which operates Gatwick’s passenger assistance contract across all airlines.
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The workers, who Unite says are paid £10.93 an hour, will strike for three days from Friday 18 August, and a further three days from Tuesday 22 August.
Unite general secretary Sharon Graham said: “Red Handling and Wilson James need to wake up and smell the coffee.
“Other employers at the airport are prepared to pay the going rate and there is no excuse why they shouldn’t do the same.
“There is no way our members will accept a real-terms pay cut and poverty pay.
“Unite’s complete focus on the jobs, pay and conditions of its members will mean that our members at Gatwick will receive the union’s unflinching support.”
A spokesperson for Wilson James described the strike announcement as “disappointing” and said it had made an “above inflation offer” to staff.
They added: “We are continuing dialog and conciliation efforts supported by ACAS, which we hope will allow us to reach an acceptable agreement for all parties.
“While we continue to engage with union partners transparently and in good faith, we are also preparing contingency plans for possible strike activity to ensure that the passengers who rely on us to support their journeys can plan with confidence.”
Unite told Sky News it was fighting for better wages “in line with members’ expectations” after those at other firms who voted to strike were handed double-digit rises.
A spokesperson for London Gatwick said: ”We are aware of the recent ballot results and encourage staff at Wilson James, Red Handling and their union to reach a resolution.
“We will support Wilson James, who hold the contract for providing assistance to passengers, in their contingency planning.
“We will also support the airlines affected, who hold the contracts with Red Handling, with their contingency plans to ensure that as many flights as possible operate as scheduled.”