US budget carrier Southwest Airlines has grounded 128 aircraft after it realised that it had missed planned inspections of its single-aisle Boeing 737 aircraft.
Southwest has notified the US Federal Aviation Administration of the lapse.
"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.
Southwest cancelled 90 flights on Tuesday due to the inspections, airline spokeswoman Brandy King said.
"Once identified, we immediately grounded the affected aircraft, initiated maintenance checks, disclosed the matter to the FAA. We are working to resolve this matter swiftly," she said.
The FAA later said it would allow the airline to continue operating the planes while the checks are being completed.
Southwest was previously ordered by the FAA to pay a record $10.2 million for flying jets on thousands of flights in 2006 and 2007 without carrying out full inspections
