Michael O'Leary, chief of budget airline Ryanair warned on Thursday that should the UK leave the EU without an agreement in place, it would cause "chaos".
"We're selling tickets for flights between the UK and Europe that may not even happen," he said. "Frankly, if there is not a deal in place by November, there will never be one." O'Leary also expressed his concerns about a "frictionless" Irish border.
Despite this month reaching an agreement with the Irish pilots' union, Fórsa, next Friday, 28 September, there will be another cabin crew strike affecting staff based in Spain, Portugal, the Netherlands, Italy and Belgium.