Federal officials have agreed to let Southwest Airlines keep using planes that missed an inspection of a backup rudder system if the planes are checked in the next five days.
Southwest grounded 128 planes -- about one-fifth of its fleet -- on Tuesday after discovering the missed inspections, airlines officials said.
According to a statement by the airline, the Boeing 737-700 jets were found to have overflown a required check.
After discovering the missed inspection, the airline notified federal safety regulators and developed a plan to complete the overdue checks. Southwest ended up canceling about 80 flights Tuesday as a result of the situation, the airline announced.
Late Tuesday night, the Federal Aviation Administration agreed to let the airline resume flying the planes while inspections are done, likely during overnight hours. FAA spokesman Lynn Lunsford confirmed that the agency approved the plan after talking with Southwest and Boeing, the manufacturer of the planes.
"The airline voluntarily removed these aircraft from service while the FAA works with Boeing and Southwest to evaluate a proposal that would allow the airline to continue flying the planes until the inspections are completed over the next few days," the FAA said in a statement.
Based in Dallas, Southwest is the nation's fourth-biggest airline.
The Associated Press contributed to this report.