Ryanair is facing a four hour strike by pilots in Germany three days before Christmas.
The Vereinigung Cockpit (VC) trade union confirmed all pilots directly employed by the airline are being asked to join a walk-out from 5.01am until 8.59am (local time) on Friday.
The damaging disruption came after the low-cost carrier narrowly avoided a strike by crew operating out of Ireland.
VC said all Ryanair flights at German airports will be affected.
The union accused the airline's management of disregarding the principles of trade union autonomy and claimed it is not committed to constructive talks.
VC said the dispute deepened after initial negotiations, scheduled for Wednesday, were cancelled at short notice over the presence of two members of its team.
Ingolf Schumacher, head of VC's industrial department, said: "Ryanair's public offer to conduct negotiations with VC can only be classified as a further publicity stunt.
"In the history of the VC, there has never been a case in which the collective bargaining autonomy has been trampled on by an employer as is now the case with Ryanair.
"This makes it clear to VC that the company is not interested in a mutually constructive co-operation, based on trust and equality. Rather, Ryanair is trying to win time and attempting to delay the beginning of collective bargaining."
VC said it regretted the disruption for passengers.
The strike was announced hours after Ryanair pledged in writing to recognise an Irish trade union - a first for the airline.
The low-cost carrier said it had sent a letter to Impact officials with proposals on pay and conditions and procedures for dealing with industrial relations disputes.
Ryanair said it was recognising both the trade union and a pilot council for employees.
"Ryanair has also submitted a set of proposals on pay and conditions, procedures and dispute resolution for its Irish-based pilots, and looks forward to concluding an early agreement on these issues with its Irish Ryanair pilot company council," it said.
The decision by one of Europe's largest airlines to deal with unions after years of opposition follows threatened pre-Christmas strike action by Irish-based pilots, which was called off earlier this week.
The airline and the union will meet on January 3 to agree a comprehensive recognition agreement.
Impact said it expected management to reach agreement on procedures quickly so the parties could move on to negotiate substantial issues around pilots' pay and working conditions.
Union official Ashley Connolly described it as a historic achievement that would resonate beyond the company.
"This advance is good news for Ryanair pilots, passengers and shareholders," she said.
"We also think it will assist thousands of workers elsewhere, who want independent workplace representation but whose anti-union employers had been encouraged and emboldened by Ryanair's previous antipathy towards Impact and other unions."