British Airways and Unite will be back around the table on Thursday (22 December) for another round of peace talks in a bid to avert strike action on 25 and 26 December from the airway's cabin crews.
A union source close to the negotiations told IBTimes UK that general secretary Len McCluskey personally intervened in the pay dispute on Wednesday and led talks for Unite.
The negotiations at mitigation service Acas went late into the night, but failed to provide a resolution.
British Airways boss Alex Cruz has said the planned industrial action will not lead to any cancellations.
"Over the weekend we have been working on detailed contingency plans to ensure that we are able to operate our normal flight programme from all our airports on both Christmas Day and Boxing Day," the chief executive said.
"We urge Unite to abandon this strike call, which is serving only to cause anxiety among our Mixed Fleet cabin crew colleagues. Our Mixed Fleet crew do a tremendous job for our customers. They earn a competitive salary package, with all crew working full-time receiving a minimum of £21,000 a year.
"We are seeking to improve this package and we encourage Unite to start a positive dialogue with us about our proposals."
Airport baggage handlers, represented by Unite, called off a planned 48-hour strike after talks with Swissport at Acas.
The action was averted after the company tabled a revised pay offer for the 1,500 staff.