Ireland's no-frills carrier Ryanair said on Thursday that its UK subsidiary has received a licence allowing it to operate in Britain in case of a no-deal Brexit.
The airline, which also reported flying nearly 140 million passengers last year, said the permit means it can "operate UK domestic and UK to non-EU routes in a post-Brexit environment, if necessary".
British Prime Minister Theresa May and the 27 EU leaders reached a draft withdrawal agreement in November that is meant to pave the way for Britain's smooth exit from the bloc on March 29.
But the deal faces strong resistance in the British parliament, which is set to vote on it later this month.
Its rejection raises the prospects of Britain leaving the bloc without an agreement, creating disruptions that threaten to hit the aviation industry hard.
London and Brussels are making contingency plans that will allow UK carriers to continue flying to EU countries even if there is no agreement on future trade and other rules.
But it would only be a bare-bones deal that does not allow UK airlines to conduct intra-EU flights.
Ryanair's UK subsidiary still stands to lose a share of the EU market, and the Irish company urged London and Brussels to agree a more thorough interim deal.
"The risk of a 'no deal' Brexit in March is rising, and despite our robust post-Brexit structures, including our post-Brexit plan around European ownership, we continue to call for the UK and EU to agree a transition deal from 31 March 2019," it said in a statement.