He blamed the problems affecting Britain's aviation industry on post-Brexit immigration policies.
Ryanair on Monday posted an after-tax profit of €170 million ($174m) for the three months to the end of June, its first profit in the quarter in three years but well short of pre-coronavirus profit levels.
“While we remain hopeful that the high rate of vaccinations in Europe will allow the airline and tourism industry to fully recover and finally put Covid-19 behind us, we cannot ignore the risk of new variants in autumn 2022,” Mr O'Leary said in a statement. “Ryanair seems unusual among the major EU airlines in summer ’22, insofar as we are fully crewed, despite operating at 115% of our pre-Covid capacity.
“Our business, our schedules and our customers are being disrupted by unprecedented air traffic control and airport handling delays, but we remain confident that we can operate almost 100% of our scheduled flights, while minimising delays and disruptions for our guests and their families.”
A lack of workers has limited flights at London's Heathrow Airport, while airlines have had to cancel thousands of flights because of a shortage of cabin crew.
“I can get visas to bring Moroccans to come in and work as cabin crew, but I can't get visas for Portuguese or Italians or Slovakian youngsters,” Mr O'Leary said.
Before Britain's February 2020 exit from the EU, Europeans could take up jobs in the country without the requirement for a visa.
One of the arguments of the pro-Brexit camp was that Britain's exit from the EU would open up jobs for Britons.
But they are not taking up the jobs as vacancies reach record highs and sectors which traditionally relied upon foreign workers, such as hospitality and agriculture, struggle to find workers.
Mr O'Leary said issuing more visas for European workers would help to ease the current disruptions in the aviation sector.
“We just need a bit of more common sense and a practical approach to how we implement Brexit,” he said.
Britain is not the only country where airports and airlines are struggling to hire enough workers.
When coronavirus restrictions nearly shut down international travel, companies cut back staff numbers to reduce costs but are now finding it difficult to rehire workers, many of whom have gone on strike to obtain better wages and conditions.