Ryanair has been issued with a UK Air Operating Certificate, which will ensure it will continue flying in Britain after Brexit.
It applied for the AOC a year ago in light of concerns over the post-Brexit environment.
But despite the CAA issuing the certificate, Ryanair repeated its call on the UK and EU to agree a transition deal from March 31 2019.
Ryanair’s Juliusz Komorek said: "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, so that any disruption to flights and British consumer summer holidays in 2019 can be avoided."
Low-cost rival Wizz Air has already secured a UK AOC while easyJet protected itself by setting up a new European company, easyJet Europe, headquartered in Vienna with an EU AOC.