Almost 1,000 workers at Gatwick Airport including baggage handlers and check-in staff will stage eight days of strikes beginning later this month.
Union Unite said the action would inevitably disrupt flights at the height of the summer holiday season.
It is set to bring further chaos for passengers, after budget airline easyJet this week cancelled around 1,700 summer flights, primarily to and from Gatwick.
Announcing the fresh strike on Friday, Unite revealed 950 workers will walk out for four days from Friday, July 28 until Tuesday, August 1.
They will then stage a second four-day walkout from Friday, August 4 until Tuesday, August 8.
A total of 4,410 flights are scheduled to depart Gatwick across all the strike days, equating to more than 840,000 seats, aviation data company Cirium said.
The airport is already suffering major disruption due to air traffic control (ATC) restrictions.
The airlines affected include British Airways, Easyjet, Ryanair, TUI, Westjet and Wizz.
The striking workers, who are members of Unite, are employed by four companies: ASC, Menzies Aviation, GGS and DHL Services Ltd.
Unite said: “Given the scale of the industrial action, disruption, delays and cancellations are inevitable across the airport.”
The union says that despite workers undertaking “highly demanding and safety critical” roles, during the pandemic companies at Gatwick carried out large-scale redundancies and cut the pay and conditions of remaining staff.
Unite has reportedly been in negotiations with the four companies since January but says they “all have failed to make offers that meets the workers’ expectations”.
Unite general secretary Sharon Graham said: “Our members at Gatwick Airport undertake incredibly demanding roles and are essential to keeping the airport and airlines working, yet their employers somehow think it is acceptable to pay them a pittance.
“As part of Unite’s unyielding focus on the jobs, pay and condition of its members the union has drawn a line in the sand and is committed to eradicating the scourge of low pay at the airport.”
Phil Lloyd, Senior Vice President UK at Menzies Aviation, said: “Sadly, Unite has rejected our earlier pay increase of 11 per cent for our ground services employees at Gatwick Airport.
“This pay award relates to our 2023 Pay Review and is in addition to the 10 per cent increase awarded in 2022. We are in continued discussions with our airline partners and remain committed to seeking a resolution.
“We have invited Unite to return to the table to continue discussions and hope to be able to reach an agreement which is workable for both the business and our employees. We will continue to work to pursue an agreeable solution to protect service to our airline and airport partners and their customers.”
A BA spokesperson said: “Our ground handling agent at Gatwick, GGS, is surprised by Unite’s announcement, given the constructive conversations they’ve had this week. It is continuing to work with the union to resolve this issue as a matter of urgency so as not to disrupt our customers’ travel plans.”
Gatwick Airport is already suffering major disruption due to air traffic control (ATC) restrictions.
Strikes, staff shortages and air space closures related to the war in Ukraine mean ATC providers are limiting flight numbers across Europe.
Gatwick is the busiest single-runway airport in the world, but its flight numbers are currently capped at peak times due to the ATC issue.
The problem recently forced easyJet to cancel 1,700 summer flights, mostly from Gatwick. The decision will affect 180,000 passengers, the Independent reported.
Earlier this week, Gatwick Airport was revealed as the “worst in the Europe” for cancellations and delays - with more than half of flights disrupted last month.
Research by passenger rights expert AirHelp found a staggering 54.08 per cent of flights from the busy London airport were cancelled or delayed in June.
It made the terminus, based in west Sussex, the worst major European airport for disruption.
Responding to news of the Unite action, a Gatwick spokesperson said: “We are aware of the recent ballot result. London Gatwick will support the airlines affected, who hold the contracts with the third-party ground handling and check-in companies, with their contingency plans to ensure that as many flights as possible operate as scheduled.”
A spokesperson from DHL Supply Chain said: "We are disappointed to hear that Unite and its members have voted in favour of industrial action at our Gatwick ground handling operation.
"However, we continue to work closely with Unite to reach a satisfactory conclusion for all parties."
