EasyJet has appointed Royal Mail boss Moya Greene to its board earlier than planned as it speeds up the search for a new chief executive.
Ms Greene, who had been poised to join the budget airline in September, will now take up the position of non-executive director with immediate effect.
She will "support the chief executive search process" after it was announced on Monday that Carolyn McCall is to join ITV in January.
In addition, Keith Hamill, who was supposed to retire from easyJet's board as non-executive director on July 31, will stay on, also to help out with the recruitment process.
Ms McCall has headed up the low-cost airline since 2010, but she leaves the low-cost carrier at a difficult time for the sector in Britain, with Brexit storm clouds gathering over the travel industry.
The pound's collapse has meant less people travelling overseas and, more starkly, British airlines are at risk of being grounded unless bumbling Tory ministers strike an aviation deal with the EU before March 2019.
Terry Pullinger, deputy general secretary of the Communication Workers Union, which represents Royal Mail workers, said: " It is extremely concerning, at a time when the business is facing huge challenges, that the chief executive of the company should have enough time on her hands to take another job.
"It will be equally offensive to our members that a highly paid member of the Royal Mail board and leader of Royal Mail Group is taking what one assumes is another lucrative contract whilst effectively saying to Royal Mail employees that they are overpaid, lucky to have a job and should accept imposed huge reductions in their pension promise.
"This feels symptomatic of the small number of industry leaders in the UK that share non-executive positions on a number of boards and are highly rewarded for shrinking rather than growing their businesses and achieving profits and bonuses as a direct result of pursuing a race to the bottom for decent working people."
A Royal Mail spokesman said: "Royal Mail has the best terms and conditions in our industry. Our management team, working with our people and our unions, is very much focused on ensuring that we keep providing great quality of service and value-for-money products for our customers. That is the best way to keep providing the best terms and conditions.
"Our CEO, as always, is highly committed to Royal Mail and has said, on many occasions, how honoured she is to serve the company. Moya's commitment is undimmed.
"We have made a very good and fair offer to our colleagues in relation to pension provision at Royal Mail. The sustainable solution we wish to put in place is about maintaining as many high quality jobs as possible at Royal Mail now and in the future."