DALLAS -- Southwest Airlines Co. resumed normal operations yesterday, a day after the carrier had to cancel 126 flights while it hurriedly performed overlooked inspections on several dozen jets.
However, not all of the 38 airplanes removed from service Wednesday returned to the skies yesterday, the carrier said.
"Four of the aircraft were held for surface repairs," spokeswoman Brandy King said. "We expect to have them back in service by the weekend."
The airline had grounded the 38 airplanes to inspect portions of their fuselages for cracks. Another five aircraft already undergoing maintenance were also being inspected, as was a jet that is being retired from Southwest's fleet.
Facing a congressional hearing April 3, the airline is discovering its own lapses and scrambling to take cautionary measures. Beth Harbin, a Southwest spokeswoman, said Wednesday that the airline's review has been exhaustive.
Wednesday's action addressed a different directive from the inspections that the airline missed last year. Southwest said it grounded the jets after confronting some confusion Tuesday night about the way the inspections should be done.
The airline visually inspected areas above and below the aircraft's windows, but noticed that the regulation also required a more sensitive test using electrical "eddy" currents that detect hidden defects.
"The inspections were done," Harbin said. "It was the method of the inspection - visual versus eddy current - that we had the question about."
Overall, the carrier canceled about 4 percent of its scheduled flights, including those for weather-related reasons.
Flights were operating normally yesterday at Baltimore-Washington International Thurgood Marshall Airport, the airline said.
Southwest chief executive Gary C. Kelly was in Washington on Wednesday to brief Robert A. Sturgell, acting administrator of the Federal Aviation Administration, about the carrier's plan to deal with its regulatory lapses, the agency said.
The FAA, which is auditing the airline's maintenance practices, fined Southwest $10.2 million last week. The airline plans to contest the fine.
In March 2007, Southwest disclosed the failures that prompted the fine. That reporting should have prompted the airline to ground the jets until they could be checked.
But with the tacit approval of an FAA supervisor in Irving, Texas, Southwest kept flying the aircraft as it performed the inspections over about eight days.
Six of the jets were found to have cracks, some as long as 3.5 inches, according to federal records. Seventy Southwest jets missed needed checks of their rudder control systems.
An aide to Rep. James L. Oberstar, the Minnesota Democrat overseeing the congressional investigation, said Southwest's actions Wednesday could have been averted if the FAA had taken strong action against the airline last year.
Oberstar is chairman of the House Transportation and Infrastructure Committee, which has blasted the FAA for regulatory lapses in overseeing Southwest. In a statement, the committee said the FAA could have headed off other problems by reviewing all of Southwest's maintenance records in 2007.
"This action by Southwest Airlines raises serious questions about whether FAA adequately followed up on the discovery a year ago that Southwest had failed to make required inspections," the committee statement said.