The boss of Ryanair says the airline will not resume flights if it has to keep middle seats empty to fight Covid-19, calling the idea "idiotic".
Michael O'Leary said he was hopeful 80% of flights could resume by October if travel restrictions are eased in July.
But he said empty seats did not ensure safe social distancing and were financially unviable.
He added that if the Irish government imposed the rule, it would have to pay for the middle seat "or we won't fly".
Like most other big airlines, Ryanair has grounded flights as countries around Europe have imposed travel restrictions to contain the pandemic.
However, industry experts believe the rules will relaxed this summer, subject to conditions.
Emirates, easyJet and Delta in the US have all said they plan to keep middle seats empty and some think governments will make it a rule.
But Mr O'Leary told the Financial Times the idea was "idiotic" as it did not ensure a safe 2 metre distance between passengers.
"We can't make money on 66% load factors," he said.
He said Europe should instead follow Asia and bring in more effective measures, such as forcing people to wear masks on transport and have their temperatures checked at airports.
Many in the airline industry believe it could take up to three years to get back on track.
According the UN's civil aviation body, ICAO, international air passenger traffic in the first three quarters of 2020 could drop by as many as 1.2 billion travellers, or by two-thirds.
But Mr O'Leary told the Financial Times he was optimistic.
He said Ryanair expects a "relatively quick recovery", with 80% of flights having resumed by September, falling to 60% in its less busy winter season.
He added that, subject to an effective coronavirus vaccine, the airline would be carrying its "2019 traffic plus growth" by summer next year.
However, he said it was likely the airline would have to cut jobs this winter and that he would continue to take a 50% pay cut beyond May if necessary.
"My pay cut will run on until the last of [Ryanair] people are off the payroll support schemes," he said.
Change to online offers
Meanwhile, the European Court of Justice ruled on Wednesday that Ryanair and other airlines must in future indicate the full price of a ticket when displaying offers online.
This means including the cost of value added tax on domestic flights and fees for check-in and payments by credit card.
The ruling came after an appeal by Ryanair against a decision by the Italian competition and markets authority, which said such charges were unavoidable and foreseeable, and should therefore be included in the price shown before booking
The BBC has approached the airline for comment.