American Airlines cancelled more than 1,000 flights on Wednesday as the reinspection of its fleet of MD-80 aircraft stretched into a second day, diverting thousands of passengers and piling expenses on a US carrier already burdened by record fuel costs.

The airline pulled its 300 MD-80s from service on Tuesday to check if the aircraft were in compliance with a government airworthiness directive, the second time in two weeks it had grounded the fleet following an audit of its records by the Federal Aviation Administration.