Thomas Cook faces strike action in a row with staff over pay, allowances and travel concessions.
The Unite union warned an industrial action ballot of over 900 staff and flight crew could start in 10 days time if the company fails to come back with an improved offer in the dispute.
The strike ballot is scheduled to start on June 11 and close on July 9, meaning that any walk-out could hit at the start of the summer peak.
The union says staff are angry over the company’s initial imposition of a pay freeze, changes to allowances and travel concessions and the company’s failure to fully address their concerns in subsequent talks.
Unite urged Cook to return to the negotiating table and begin to address staff concerns to avoid a strike vote.
Unite national officer for aviation Oliver Richardson said: “Staff are working hard in difficult circumstances, but feel let down by the imposition of detrimental changes and a pay freeze.
“A strike vote is a last resort. We would urge management to get back around the table and start to seriously address the concerns of staff over detrimental changes and a pay freeze, allowances and travel concessions.”
A spokesperson for Thomas Cook UK & Ireland said: “We have asked all our staff in the UK for their understanding and support while we effect the necessary changes to return Thomas Cook to a position of strength in the UK.
“We have gained that understanding and support from the vast majority of our people. We believe that the cabin crew in the UK understand the challenges facing the business.
“Whilst the Union canvass their members we’d like to stress from now that even in the unlikely event of any action being taken, there will no disruption to customer’s holidays.
“It’s hugely disappointing that Unite is attempting to scupper our UK turnaround plans but we remain available to talk to them.”