American Airlines subsidiary PSA Airlines cancelled more than 200 flights after grounding most of its fleet due to an urgent maintenance issue.
The issue relates to the nose gear door on its Bombardier regional jets.
The airline voluntarily informed the Federal Aviation Administration and has been working with the FAA to ‘immediately address the issue’ American said.
"We are working with our customers to arrange new accommodations on other flights, and we are working to return the impacted aircraft to service."
PSA Airlines operates more than 100 Bombardier CRJ700 and CRJ900 aircraft.
Inspections of all the aircraft are expected to be completed before the first scheduled flights on Friday 29 January, but it still may lead to more flight disruption.
It led to more than 200 flight cancellations on Thursday.
PSA operates flights for AA under the American Eagle regional brand name.
Written by Ray Montgomery, US Editor
