American Airlines said Thursday it expects a massive round of flight cancellations to extend into Saturday, but added that all the grounded aircraft were expected to be back in the air by Saturday night.

The Texas-based airline said it canceled 922 flights Thursday to fix faulty wiring in hundreds of jets and would cancel another 570 flights on Friday.

This week, Federal Aviation Administration inspectors, who have been conducting stepped-up surveys of compliance with safety rules called airworthiness directives, said 15 of 19 American jets they examined flunked. That left the airline no choice but to ground all 300 of its MD-80s, the most common jet in its 655-plane fleet.

"We have obviously failed to complete the airworthiness directive to the precise standards that the FAA requires, and I take full responsibility for that," said Gerard Arpey, American's chairman and chief executive.

"We apologize for the inconvenience this has caused our customers," Arpey said. "American will do whatever it takes to assist those affected by these flight changes and our employees are working hard to ensure that we remain their choice for air travel. This includes compensating those inconvenienced customers who stayed overnight in a location away from their final destination."

The airline also advised customers who had to stay overnight to go to its Web site to get information about compensation.

Counting Friday's cancellations, American has scrubbed more than 3,000 flights since Tuesday. It said 100 of its 300 MD-80s had been inspected and were back in service as of Thursday morning. The airline said it expected an estimated 130 MD-80s to be in service by Thursday evening.

It said all of its MD-80s were expected to be in service by Saturday night.

It was estimated that more than one in three American Airlines flights have been canceled over the last three days. On Wednesday, American canceled more than 1,000 flights, nearly half its schedule. On Tuesday it canceled about 460 MD-80 flights.

It's the second wave of cancellations at American over the wiring. At issue is how the cords used to secure bundles of wires for the auxiliary hydraulic systems are spaced and lined up.

The FAA has tightened inspections of planes at all U.S. carriers since the agency came under fire for letting Southwest Airlines fly planes that had missed safety inspections. American and Delta Air Lines both canceled flights in late March to perform wiring-related inspections and repairs.

Other carriers flying MD-80s have followed American's example.

Midwest Airlines grounded 13 airplanes Thursday to reinspect a wiring harness, while Alaska Airlines said it canceled 14 flights Wednesday to conduct wiring inspections on its nine MD-80s.

Midwest Airlines voluntarily canceled all of its flights involving the Boeing MD-80 aircraft on Thursday to make sure the wiring component is in compliance with a recent Federal Aviation Administration directive.

A Delta Air Lines spokeswoman said the airline was likely to ground "a handful of flights" Thursday as well.

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• American Airlines