Workers providing assistance to passengers with restricted mobility at Heathrow Airport are to strike for four days in a dispute over pay.
Unite said around 500 of its members employed by private firm Wilson James will walk out from April 5.
The union said the workers are being paid less than Wilson James staff at Gatwick Airport performing the same role.
Unite general secretary Sharon Graham said: “Wilson James and Heathrow are both highly profitable, so there is absolutely no excuse for these workers to be paid far less than their colleagues at Gatwick. Unite is backing these workers 100% in their fight for fair pay.”
Unite warned that further strikes will be held if the dispute is not resolved.