Southwest Airlines Chief Executive Gary Kelly apologized to customers and safety regulators for maintenance lapses which led to a government penalty, the Wall Street Journal reported on Friday.
"I am not satisfied we are as compliant" with maintenance requirements "or as safe as we could be," Kelly said in an interview with the newspaper.
"We will certainly be very cooperative in working with the (Federal Aviation Administration)," he said.
Southwest grounded more than three dozen planes on Wednesday due to a new glitch in safety inspections.
The groundings, which cut 4 percent of its scheduled flights, came after the FAA last week proposed a record USD$10.2 million fine against the airline, charging it missed deadlines to inspect planes for structural flaws during 2006 and 2007.