Ryanair has agreed to recognise a union to represent its 600 UK-based pilots for the first time.
The Irish airline had previously refused to recognise the British Airline Pilots' Association (Balpa).
However, Ryanair said last month it was prepared to recognise pilot unions in a bid to avert strikes over Christmas.
Balpa general secretary Brian Strutton said the agreement was historic "given Ryanair's previous hostility towards unions".
"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," he said.
The UK accounts for about a quarter of Ryanair's pilots and planes, with Stansted its biggest base.
Eddie Wilson, the airline's chief people officer, said: "The fact that we have delivered pay rises of up to 20% and union recognition for our pilots in our largest market shows how serious Ryanair is about working constructively with unions that are willing to work constructively with us."
Balpa will elect five union representatives who will lead future negotiations on issues such as pay, hours, rostering and holidays with the airline.
It will also hold a ballot for an advisory group for contractor pilots not employed directly by Ryanair.
The union recognition follows a torrid period for Ryanair, which cancelled thousands of flights late last year in the wake of a pilot shortage sparked by rota issues.
In October, Ryanair chief executive Michael O'Leary wrote to its pilots offering them better pay and conditions to stay with the airline.