American Airlines parent AMR said it expects to have all of its MD-80 jetliners back in service by Saturday night.
American Airlines' fleet of MD-80 aircraft has been grounded for wiring inspections, forcing the cancellation of thousands of flights over the past three days.
Chief Executive Gerard Arpey told a conference call with reporters that American is trying to stay ahead of the problem "as best we can" but inspections and related work takes time.
The Federal Aviation Administration must inspect each plane before it returns to service.
Arpey did not have a firm figure for the financial impact of the disruption so far, but believes it will "be in the tens of millions of dollars."
Arpey also said American would "take a look" at accelerating replacement of its nearly 300-strong MD-80 fleet with new Boeing 737s.
AMR shares were recently trading higher.
This week's flight cancellations by American Airlines are likely to spread to other U.S. airlines in the weeks ahead as federal regulators step up a by-the-book review of carriers' compliance with maintenance and safety orders issued in recent years.
"If we do uncover any safety issues from these audits, the carriers will have to make a business decision as to how to deal with the issue," Federal Aviation Administration spokesman Les Dorr said.
Midwest Airlines on Thursday became the latest airline to ground planes and cancel flights to re-inspect a wiring harness, the same issue that has forced American to cancel more than 2,400 flights.
On Capitol Hill, Nicholas Sabatini, the FAA official who ordered the audits last month after Southwest Airlines was found to have flown planes that missed inspections, will likely face tough questions from senators much like those he encountered last week during a House hearing that featured whistleblower testimony.
The first round of audits, conducted over a two-week span last month, checked 10 airworthiness directives that apply to each carrier's fleet. The second phase, which runs through June 30, will check 10 percent of the orders that apply to each airline's fleet. For a large carrier like American that operates many different aircraft, that could be several hundred directives, Dorr said.
Depending on how you look at it, this could be viewed as a classic bureaucratic overreaction after the agency was embarrassed by the disclosure last month that FAA inspectors were letting Southwest ignore airworthiness directives -- or that the top brass, shocked at how lax the safety review system had gotten, has finally awakened and ordered a high-impact new way of doing business.
"We are aware and sympathetic ... 100,000 people being stranded is extraordinary," said FAA spokeswoman Lynn Tierney. "But the role is clear, it's a regulator's role and you have to enforce the regulations. We understand the disruption this causes, but (the airlines) had 18 months to complete the work."
Tierney is referring to the safety order issued on the Boeing . MD-80 aircraft that have been grounded by American, Midwest and other airlines in recent days. The FAA issued an airworthiness directive on those planes after reports of shorted wires, evidence of worn-down power cables, and fuel system reviews conducted by the manufacturer. It was effective Sept. 5, 2006, and the airlines had 18 months to comply.
The fallout could be seen at airport ticket counters, where frustrated customers bickered with American employees.
Airline executives said they thought they had fixed the wiring two weeks ago, when they canceled more than 400 flights to inspect and in some cases fix the shielding around the wires in their MD-80 aircraft.
But this week, Federal Aviation Administration inspectors, who have been conducting stepped-up surveys of airline 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 American's 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," Gerard Arpey, American's chairman and chief executive, said at an industry event in California.