Michael O’Leary said there could be “months” of chaos with planes not being allowed to fly to and from mainland Europe.
Speaking on CNBC, he bashed the result of the EU referendum despite 17.4million people voting to exit the trading bloc.
He said: “I really worry, I think Brexit is an impending disaster, it’s quite clear the British have no idea what they’re doing.
“In our industry, it looks like they don’t want to obey the European Court of Justice rulings, which mean they leave open skies and there is no way in my view Britain can negotiate a bilateral with Europe to allow flights to operate in a 12 or 18-month period.
“We may well have a period of weeks or months after March 2019 where there will be no flights to and from Britain.
“And this is the kind of crazy scenario we’re dealing with.”
The airline boss ripped into Theresa May’s government over its Brexit strategy and warned the EU would not be kind to the UK.
He said: “You talk to British ministers ‘have you got a plan B?’ – ‘er no’.
“And the Europeans are absolutely four-square going to do as much damage to Britain as they can to dis-encourage anybody else leaving the European Union.”
The comments come after Ryanair’s chief marketing officer Kenny Jacobs called on the Government to give airlines “clarity” over Brexit and warned an “ugly” divorce could lead to “no flying between Europe and the UK”.
He told BBC Radio 4: “If there isn’t a new bilateral in place, you may have very restrictive or no flying between Europe and the UK for a period.
“And I think It’s clear we’re heading to what looks to be a very ugly divorce at the moment.”
