The chief executive officer of Southwest Airlines, one of the biggest US carriers, insisted on Sunday that customers could fly in safety again and added that air traffic was slowly reviving, which was almost totally crippled by the coronavirus pandemic.

Asked on CBS if it was safe to travel again, Gary Kelly responded, "It is, and we are doing everything we can to enable people to return and fly." According to Kelly, Southwest was taking a variety of safety precautions: passengers and crew members would be forced to wear masks; aircraft would receive deep cleaning between flights; and certain seats will be left vacant to allow for a degree of social distance.

Kelly said the company's fleet of jets are now being subjected to "very deep cleaning" every night, and workers and passengers will be required to wear masks. He also said the airline will not have planes operating to their full capacity.

Airlines are facing a bleak outlook and collapsing demand from passengers as the travel months near. Last week, Southwest posted a net first quarter loss of $94 million, while advising investors the coronavirus pandemic is projected to "even more dramatically" affect second quarter results than the start of the year.

Despite agreeing to accept about $3.3 billion in government aid under the CARES Act, Kelly told Southwest workers that the funding will not entirely compensate payroll expenditures through September and the airline must be ready to become "drastically smaller" if efficiency does not change "dramatically" from May to July.

Planes across airline companies taking to the skies average 17 passengers per flight, CBS data show, and in the first quarter, Southwest Airlines posted losses of more than $90 million.

Kelly said that his airline has a strong balance sheet, plenty of capital, a good business structure, and a low-cost system that will improve the organization as Americans' fear of coronavirus affects the dynamics of the airline market.

Kelly's comments came after other major airlines, including Delta, United, American, and JetBlue, revealed that travelers would have to wear face masks on flights and that other health measures would be implemented against the coronavirus.

The virus has struck the airline industry hard, reducing air travel to a bare minimum amid lockdowns and travel restrictions - and Southwest is no exception. During the shutdown, Kelly said that about 400 of the airline's fleet were grounded.

Southwest has been granted $3.2 billion in government emergency assistance and has sought an additional loan, but Kelly said he was not sure it would be required.