Fresh chaos for US air passengers
American Airlines has cancelled nearly 2,500 flights since Tuesday
The US's biggest airline has cancelled 900 more flights after safety concerns forced it to ground 300 planes - nearly half its passenger-carrying fleet.
It is the third day of cancellations by American Airlines. Nearly 2,500 flights have been affected, causing delays for 100,000 passengers.
The action follows an inspectors' warning of problems with wiring repairs on the MD-80 aircraft two weeks ago.
Other major US carriers have also been forced to ground planes for inspection.
Alaska Airlines has cancelled more than 40 flights, and Midwest Airlines 10, to inspect their own MD-80 jets.
Delta Air Lines, which operates 117 of the twin-engined craft, was likely to call off "a handful of flights", the Associated Press reported the airline as saying.
Full responsibility
American Airlines has said the cancellations are likely to continue until Saturday.
Chief Executive Gerard Arpey apologised profusely for the inconvenience to passengers.
"We are doing everything we possibly can to reaccommodate our customers," he said.
"It's my fault and I take full responsibility."
Mr Arpey added that the cancellations would cost the airline "in the tens of millions of dollars".
The Federal Aviation Administration (FAA) has been tightening up its inspections since it was discovered last year that fuselage cracks on Southwest planes had gone undetected because of missed inspections.
The FAA said it had checked several American MD-80s a fortnight ago and decided that improvement work carried out did not meet its standards.