In a stinging attack, the controversial airline chief executive said many people were woefully ill-informed of the impact of leaving the EU.
He told a meeting of fellow airline leaders in Brussels: “When you begin to realise that you’re no longer going to have cheap holidays in Portugal or Spain or Italy, you’ve got to drive to Scotland or get a ferry to Ireland as your only holiday options, maybe we’ll begin to rethink the whole Brexit debate.”
O’Leary has raised concerns before that flights in and out of the UK will be grounded if a Brexit deal fails to address the travel industry.
Britain will no longer be covered by the EU Open Skies agreement that allows airlines to fly into and out Europe without restrictions.
Now O’Leary has gone further by suggesting deliberately grounding fleets to show consumers the real potential impact of Brexit.
“I think it’s in our interests – not for a long period of time – that the aircraft are grounded,” he told the audience of his peers.
“It’s only when you get to that stage where you’re going to persuade the average British voter that you were lied to in the entire Brexit debate.
“You were promised you could leave the EU and everything would stay the same. The reality is you can leave the EU, yes that’s your choice, but everything will fundamentally change.”
He said by grounding fleets it would create an opportunity to refocus the debate. Ryanair carries about 130 million customers a year, operating 1,800 routes to 34 countries.
Carsten Spohr, the boss of German carrier Lufthansa, backed the threat, saying: “In theory, if we could use this industry to prove to the British how wrong the decision was, that might be a good thing.”
Transport secretary Chris Grayling said in January that he was confident flights would not be grounded because “it’s in the interests of everyone” to maintain the open market for aviation.