Ryanair has today signed a formal union recognition agreement with the British Airline Pilots Association (BALPA).
BALPA will now be the sole representative body for Ryanair pilots in the UK.
It follows the budget airline's decision late last year to begin recognising unions - a major departure from the company's previous policies.
The decision came as the airline worked to avert a planned strike by pilots over the Christmas period.
Today, the company says the agreement with the British union shows Ryanair can work with unions that wish to work with them, and welcomed the "positive and constructive engagement of BALPA".
In a statement, Brian Strutton, General Secretary of BALPA, said: “Given Ryanair’s previous hostility towards unions, today’s agreement is an historic one.
"While we were initially sceptical about Ryanair’s sincerity in offering recognition to us and other unions, our conversations and meetings with them have shown that they are genuine in wanting a constructive trade union relationship."
Meanwhile, Ryanair’s Chief People Officer Eddie Wilson said: "This rapid progress in the UK is in marked contrast to some other EU countries where we are still waiting for a response to our recognition proposals and where some unions have failed to put these substantial pay increases to our pilots.
"We now call on these unions to stop wasting time and act quickly to deliver 20% pay increases to our pilots in February, and conclude formal recognition agreements".
In December, Ryanair wrote to IMPACT - which includes the Irish Air Line Pilots' Association (IALPA) - setting out its plans to recognise the pilots’ union.
The Irish Times reports that formal recognition agreements with IALPA and other European groups could take weeks to complete.
Members of IALPA, meanwhile, will meet today to discuss the 20% pay offer from Ryanair.