IMPACT has given Ryanair until midday today to come up with a document and said strike action can be implemented in the absence of a timely agreement.
One of the pilots was a contractor and one a direct employee, but Ryanair has ended both of their contracts, VC said.
The pilots plan to hold a warning strike between 5 am and 9 am (0400 and 0800 GMT) on all of the Irish carrier's services from German airports. We advise all customers in Germany to turn up as normal tomorrow, as we plan to operate all scheduled flights, and we will be doing our upmost to minimise any disruptions to the Christmas travel plans of our German customers.
"This has shown us that nothing has changed with Ryanair's management style or how it handles workers' rights", VC President Ilja Schulz told reporters, sitting behind a table bearing the slogan "No landing clearance for Irish social dumping".
"Ryanair continues to play for time and as a result prevents the launch of collective bargaining", said VC negotiator Ingolf Schumacher.
In a letter to the union obtained by Bloomberg, Eddie Wilson, Ryanair's chief people office, proposed an agenda for the January meeting while saying the union delegation should be composed of VC officials and "currently employed Ryanair pilots in Germany".
"This makes it clear to VC that the company is not interested in a mutually constructive co-operation, based on trust and equality. In normal industrial relations, we do engage on proposals around pay and that maybe part of our discussions with management going forward, but, I think, it's too early to say".
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It follows landmark talks between unions and management on Tuesday when the airline said it would also recognise cabin crew unions as well as those of pilots.
The airline said in a statement that the planned walkout is "unjustified and unnecessary" and that it had written to the union agreeing to meet again in Frankfurt Jan. 5.
Ryanair said it had written to the Impact union in Ireland on Thursday to confirm recognition of the union and a joint council for Irish pilots.
Ryanair has also offered to hold talks on January 5 but Schulz said those talks were subject to the same conditions and so the strike would go ahead.
Once that is agreed, IMPACT says, it intends to "move on to negotiate substantial issues around pilots' pay and working conditions".
Commenting on the official recognition of the union by Ryanair, IMPACT official Ashley Connolly described it as a "historic achievement" that would resonate beyond the company.