BRUSSELS/CHICAGO (REUTERS) - The European Commission will next month present a set of rules for the safe reopening of air travel when coronavirus lockdowns end, including social distancing in airports and planes, while some US airlines are taking their own protective measures.

EU Transport Commissioner Adina Valean said on Wednesday (April 22) that measures under consideration would include the wearing of masks and disinfection of planes and airports.

"All this should be part of those guidelines and probably by mid-May we can put forward this strategy we are working on,"Valean said on Twitter.

The move came as debate heats up in the United States, the world's busiest domestic market, on how to apply rules on social distancing or protective gear to air travel.

It is unclear if the Federal Aviation Administration has the authority to compel passengers or flight crews to wear face coverings on airplanes.

Last week, FAA Administrator Steve Dickson told a pilots'union that the agency and the US Centres for Disease Control and Prevention planned to update guidance for airline flight crews amid concerns from pilots, but regulators are not mandating new safety requirements.

Some US airlines have implemented their own measures including blocking middle seats, pausing automatic upgrades and changing the boarding process.

Delta Air Lines would like to see consistency among government requirements to help streamline processes for passengers and employees, a spokeswoman said on Wednesday.

Earlier, Delta chief executive officer Ed Bastian warned of a choppy recovery in air travel that would ultimately depend on people feeling safe.

"When you ask people, what's the most important thing to get them to start traveling again, it's going to be confidence in their safety," Bastian said on a conference call after the carrier posted its first quarterly loss in eight years.

Delta is encouraging passengers and employees to wear protective gear, Bastian said, noting that at least 80 per cent of its customers now wear face masks when they travel.

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In Canada, regulators started requiring passengers on Monday to wear a non-medical mask or face covering during the boarding process and flights.

BLOCKING MIDDLE SEATS

In Europe, Ryanair chief executive Michael O'Leary has described proposals for planes to fly with empty middle seats when the coronavirus travel restrictions end as "mad," saying they would be "hopelessly ineffective" as well as unaffordable.

Instead, the company backs the introduction of mandatory temperature checks and masks for passengers and crew when flights resume.

Airlines have raised concerns that measures to slow the spread of the pandemic could blight profitability long after the travel restrictions end. The International Air Transport Association (IATA) estimated that the crisis could cost airlines a total of US$314 billion (S$450 billion).

The EU's Valean said it was impossible to say when the industry could resume operations, but noted that she expected social-distancing requirements to remain in place for as long as there is no Covid-19 treatment or vaccine.

"We expect the crisis to stay with us and the virus to stay with us," she said.