April 10 (Bloomberg) -- AMR Corp.'s American Airlines scrubbed 933 more flights today, adding to 1,550 already canceled this week, as it continued aircraft wiring repairs and groundings that have stranded more than 273,000 passengers.

American said it had ``no choice'' in parking its 300 Boeing Co. MD-80 jets, almost half its fleet, after the planes again failed to meet a U.S. safety order. The carrier canceled about 570 flights for tomorrow and may have more on April 12 before all of its MD-80s are back in service late that day.

Compensating fliers and fixing jets will cost ``tens of millions of dollars,'' Chief Executive Officer Gerard Arpey said. ``We have fought our way through many difficult circumstances over the years and we will fight our way through this one.''

Federal Aviation Administration whistleblower complaints that spurred a safety audit at 117 airlines and caused at least four carriers to ground planes sent a wake-up call to regulators and an industry that had grown complacent about maintenance, a former top safety official said.

``The airlines and FAA have spent too much time talking about how safe the system is without trying to ensure the continued safety,'' James Hall, former chairman of the National Transportation Safety Board, said in an interview yesterday. ``This is kind of a spanking, and that's certainly better than an accident.''

`My Fault'

AMR's groundings came in response to spot checks by the FAA that found the world's largest carrier hadn't secured some wiring in accordance with an agency directive.

``It's my fault,'' Arpey said in a news conference today. ``We failed to fix it.''

The MD-80s are safe, and the public can have confidence in American's safety, Arpey said. ``I put my kids on these airplanes all the time.''

By 6:30 p.m. New York time, 132 MD-80s were returned to service, the Fort Worth, Texas-based carrier said. The planes, flown mostly on domestic routes, account for 46 percent of American's total, and idling them erased 40 percent of the carrier's 2,200 flights today.

American hired an outside consultant to review its compliance with FAA directives and is conducting an internal investigation. No changes in maintenance personnel are planned ``at this point,'' said Roger Frizzell, American's vice president of corporate communications.

Other Groundings

Midwest Air Group Inc. grounded its 13 MD-80s for inspections and canceled 14 flights today. The Oak Creek, Wisconsin-based carrier hoped to have inspections completed by the end of the day, spokesman Michael Brophy said. MD-80s make up 34 percent of Midwest's fleet.

Alaska Air Group Inc. canceled 11 flights, on top of 31 dropped since Tuesday night, to continue checks on its nine MD- 80s, spokeswoman Caroline Boren said in an interview. The Seattle-based airline is ``not anticipating major schedule impacts tomorrow,'' she said.

Delta Air Lines Inc. has completed inspections of its 117 MD-88s, which are part of the MD-80 family, spokeswoman Betsy Talton said. The Atlanta-based carrier canceled a ``handful'' of flights, she said, without being more specific. Twenty of Delta's MD-88s required additional work, Talton said.

AMR rose 70 cents, or 7.6 percent, to $9.87 at 4:15 p.m. in New York Stock Exchange composite trading. The shares have plunged 69 percent in the past year.

Customers booked on canceled flights may request a refund or $500 voucher toward future flights, American said. Those with flight reservations through tomorrow can rebook without charge. The airline is paying for hotel stays for passengers stuck overnight.

Back Burner

``This would be a big item normally, but in the age when oil is jumping $10 a barrel in one week and you have an uncertain economy, this is really on the back burner as far as serious cost items go,'' Ray Neidl, a New York-based analyst at Calyon Securities Inc., said in an interview. ``Whatever it might cost them during this ordeal could be completely reversed very easily if oil went down $10 a barrel.''

Falling short of FAA requirements for the wiring adjustments in an earlier round meant that American didn't have the option of parking some jets on a rotating basis while flying others, Arpey said yesterday. American checked all the MD-80s in March in response to the FAA order, resulting in groundings and hundreds of scrapped flights.

Senior FAA officials were questioned by U.S. senators today on whether they did enough to improve oversight after whistleblowers disclosed flaws at Dallas-based Southwest Airlines Co. Southwest may be fined a record $10.2 million for operating 46 planes that it failed to check for fuselage cracks.

The FAA, which reassigned a manager over the Southwest lapses, hasn't determined whether it will fire or move any more employees, safety chief Nicholas Sabatini told the Senate panel.

``We will examine everything surrounding this circumstance and will take whatever action needs to be taken,'' he said.

Sabatini and FAA colleagues were scolded by Jay Rockefeller, a West Virginia Democrat who chairs the committee.

``The American people put their trust in you,'' he said. ``In recent weeks, that trust has been put to a severe test.''

To contact the reporters on this story: Mary Schlangenstein in Dallas at maryc.s@bloomberg.net; John Hughes in Washington at Jhughes5@bloomberg.net

Last Updated: April 10, 2008 19:21 EDT