DALLAS (AP) -- American Airlines on Saturday received clearance from federal aviation officials to return all of its 300 grounded jets to service, an airline spokesman said.
After 200 cancellations Saturday morning, Fort Worth-based American was running a full schedule by the afternoon with no cancellations, said spokesman Charley Wilson.
Starting Tuesday, the nation's largest airline canceled nearly 3,300 flights, as it grounded 300 MD-80 jets to wrap wiring bundles to meet federal safety standards and prevent fires.
The cancellations stranded hundreds of thousands of people during the week.
American said 226 of its MD-80s were back in service by Friday morning. By noon on Saturday, the airline had received clearance to return all the remaining grounded jets to service, Wilson said.
The groundings had come as a surprise.
American officials said they thought they had the needed repair work completed two weeks ago when it scrubbed more than 400 flights, but the Federal Aviation Administration said the wiring still was not secured and stowed properly in wheel wells.
Gerard Arpey, chairman and chief executive of American parent AMR Corp., said the costs of the cancellations to American will run into the tens of millions of dollars - including vouchers to reimburse stranded customers, overtime for maintenance crews and lost revenue. An analyst with Standard & Poor's estimated it could easily top $30 million.
Arpey said that neither American's mechanics nor the FAA were to blame for the groundings, and he said he took responsibility for the cancellations. He said the company would hire a consultant to help it comply with FAA safety rules in the future.
American's entire fleet averages 15 years in age, making it the second oldest in the industry behind Northwest Airlines, according to regulatory filings by the airlines.
Arpey said Thursday that American may accelerate the replacement of its MD-80s, but only because newer planes get better mileage, an important consideration with fuel at record prices. The CEO said the recent groundings were not a factor in the decision to replace MD-80s.
© 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Learn more about our .
Some questions and answers about the groundings: Q: What prompted the FAA to issue the order on the MD-80 wiring bundles? A: Reports of shorted wires, evidence of worn-down power cables, and fuel system reviews conducted by the manufacturer, Boeing Co. The airworthiness directive carried an effective date of Sept. 5, 2006, and airlines had 18 months to comply. Q: What could happen if the wires shorted out? A: Besides the loss of auxiliary hydraulic power, a fire in the wheel well of the airplane could be sparked by a short from the wires. The actions required by the government also are intended to reduce the possibility of fire or a fuel tank explosion that would destroy the plane, according to the FAA. Q: Why were airlines given 18 months to comply? A: Officials assessed the risks that the wires posed, and in the case of those that are near, but not inside a fuel tank, they determined that carriers would have 18 months, said FAA spokesman Les Dorr. Two things are required for an explosion â€” fire and the proper mix of fuel and air â€” and the wire bundles inspected in the MD-80s were not in a position where an explosion was likely, he added. Q: Why didn't the airlines comply by the deadline? A: Assuming the airlines received and understood the FAA order, "the likely answer is they believed they didn't have to," said Daniel Petree, dean of the College of Business at Embry-Riddle Aeronautical University in Daytona Beach, Fla. In general, businesses don't like to take on extra costs "if there is no payoff for them in doing it." The carriers likely also assessed the risks to their fleet and weighed that against disrupting service on planes that already yield little revenue per seat. Brian Stirm, director of aircraft maintenance at Purdue University's aviation technology department, added that 18 months was "more than adequate time to do a visual inspection." Even untrained mechanics and inspectors could identify chafing, which is the "wire bundle rubbing on something else," he added. Q: What did it cost to comply, and how many aircraft were affected? A: More than 1,000 airplanes worldwide were affected, including an estimated 732 in the U.S. Based on the required parts and labor time, the FAA estimated the cost to U.S. operators would be up to $1,304 per airplane. While that figure may seem small, the FAA did not factor in revenue lost to the airlines if the planes are taken out of service, Petree said â€” something the carriers likely did. Removing an aircraft for 12 hours could mean losing up to five trips, and having to compensate passengers for cancellations and missed connections with hotel rooms and other perks, he said. Q: Didn't wiring problems lead to the explosion and crash of TWA Flight 800 that killed all 230 people aboard in July 1996? A: Yes, but the explosion in the fuel tank of that plane, a Boeing 747, most likely came through a different wiring system, according to the National Transportation Safety Board. Air-conditioning units underneath the fuel tanks also are believed to have heated the vapors inside the tank, which made them more vulnerable to explosion.