Thomas Cook Airlines cabin crew are voting on possible strike action during the May half-term school holidays in a dispute over health and safety after changes to their rest breaks.
Cabin crew will be allowed one 20-minute break over 12 hours, according to the Unite union, and more than 1,000 cabin crew have begun voting in a ballot for industrial action.
The union said staff were previously entitled to a 20-minute break every six hours.
The ballot of staff who work on flights from 10 airports across the UK closes on May 25, and could lead to industrial action taking place during half term.
Unite said there were mounting concerns that cabin crew were being “pushed to the limit in an attempt to maximise profits”.
It accused the travel company of a “repeated refusal to agree to talks and reach a sensible negotiated solution”.
A Thomas Cook spokesman told The Guardian: “We would like to reassure our customers that nothing matters more to us than safety.
“It’s regrettable the union has chosen this path because the crew rest procedure, which includes monitoring all crew rest on all flights, was introduced with the agreement of the union.
“It also meets the regulations of industry experts the Civil Aviation Authority and does not compromise on safety.
“We have offered to meet union representatives and the message we hear directly from our crew is that they’re looking forward to a great summer of flying customers on holiday.”
The union’s national officer, Oliver Richardson, said: “Our members are deeply concerned about the impact these changes to rest breaks are having on inflight safety. Fatigue is a major contributory factor to accidents and slower response times when there is an incident.
“The primary purpose of cabin crew is the safety of passengers, but instead Thomas Cook seems intent on working them to the bone to extract as much money as possible out of passengers at the expense of safety.”
Cabin crew typically work shifts of 10-15 hours and up to 60 hours a week. Shifts include pre-flight preparations, safety and security checks, boarding, inflight service of headsets, drinks, food, duty-free sales and other promotions.
Thomas Cook has introduced an Airshoppen service. This additional inflight service allows passengers to order goods online before their flights and have them delivered to their seats. It involves cabin crew sorting and bagging orders before takeoff and collecting payment during the flight. The service could take up to two hours to deliver, Unite said.