Enrique Beltranena, CEO of Volaris, Mexico's biggest carrier by passenger traffic, told Reuters in an interview he believed the country had already begun making improvements to its safety oversight before Tuesday's downgrade was formally announced.

Asked whether he thought Mexico could recover its top category rating within six months, he said: "I would hope it would be less than that" and argued the country was in a better position than when it suffered a downgrade in 2010.

On that occasion the downgrade lasted about four months.

"I would expect it to be a much faster process, much more effective," he said.

While the downgrade was not helpful, Volaris's business would be virtually unaffected, and it would add more flights in Mexico and Central America in the coming months, even as the decision put the brakes on U.S. expansion, he said.

Volaris was sticking to its second quarter operating forecast in spite of the downgrade, Beltranena said.

(Reporting by Dave Graham and Noe Torres; Editing by Sonya Hepinstall)