“Flybe, whose headquarters is in Exeter, is warning that no agreement is in place for services to mainland Europe after Brexit.
With only eight months until Britain leaves the EU, airlines have no legal, commercial or political deals in place.
Flybe said it was already selling fares for next summer, with fingers crossed that common sense would prevail. But it warned there was no certainty.
Chief commercial officer Roy Kinnear said: “Customers are used to buying their flights in advance.”