With tens of thousands of passengers inconvenienced at the nation's airports this week, aviation experts are at odds today over whether airlines should have canceled so many flights.
American Airlines called off nearly 3,000 flights this week to reinspect wiring on the carrier's MD-80 jets. Delta, Midwest and Alaska airlines also canceled flights this week for inspections, though in smaller numbers than American.
But were wiring concerns serious enough to warrant such massive cancellations? Should the airlines have inconvenienced so many people at once? Was the flying public's safety actually at risk?
If aviation experts agree on anything today, they agree on this: It's a slippery slope.
Jim Hall, a former chairman of the National Transportation Safety Board, said it's crucial to make sure the little things don't add up.
"Aviation is certainly precise and very unforgiving at 35,000 feet," Hall said.
Nicholas Sabatini, the Federal Aviation Administration's associate administrator for aviation safety, told Congress Thursday that carriers are required to follow the strict letter of the law. If they don't, they cannot fly.
"They made the right decision," Sabatini said Thursday. "They put those aircraft on the ground until they could demonstrate compliance."
Bundling Wires in the Wheel Wells
After TWA flight 800 crashed off the coast of Long Island in 1996, the FAA required manufacturers to take a closer look at fuel tanks and wiring.
That wiring is at the center of the cancellations this week, as inspectors again make sure that thick bundles of wires in the wheel wells are secured at precise intervals and, where necessary, wrapped with appropriate protective sleeves.
American is reinspecting its planes after securing the wire bundles a quarter of an inch too far apart. Delta found it had an issue with the protective sleeving it was supposed to have wrapped around a certain part of the wire bundles.
The details are minute, but the worst-case scenario of not following directions is made clear in the FAA-issued airworthiness directive at the center of the flap: "We are issuing this AD to prevent shorted wires or arcing at the auxiliary hydraulic pump, which could result in loss of auxiliary hydraulic power, or a fire in the wheel well of the airplane," the directive states.
The maintenance requirement is "intended to reduce the potential of an ignition source adjacent to the fuel tanks, which, in combination with flammable fuel vapors, could result in a fuel tank explosion and consequent loss of an airplane," the directive also says.
In other words, the worst-case scenario is that the wires chafe against each other. The chafing causes a spark. The spark sets off a larger fire and the fuel tank explodes. The worst-case scenario is that the plane could fall from the sky.
But there's no indication American was headed down that path.
"In no case did we find chafing of the wires," American chairman and chief executive Gerard Arpey said Thursday afternoon.
A Flight Safety Issue?
After receiving reports of shorting or arcing on wires located in the wheel wells of those planes, the FAA issued this particular requirement in September 2006 that called on airlines to comply with the one-time wiring inspection. The airlines were required to complete that inspection by March 2008.
John Eakin, aviation safety consultant and president of Air Data Research in Helotes, Texas, spent this week looking over the reports issued in the years before 2006 that prompted the FAA to issue the requirement in the first place.
The reports were not serious enough a problem to prompt this week's mass cancellations, Eakin said.
"What I see is just routine stuff," said Eakin, who has worked as a pilot and mechanic for 40 years. "I don't have any sense that there was any imminent danger of the airplane falling out of the sky, if you will. That's not to say that it couldn't. Obviously, someone along the way has determined that this has the potential to cause serious damage."
"I would think that if it was likely to cause a problem, they wouldn't have taken six or seven or eight years to do the paperwork," Eakin said.
When flight safety is not likely an issue, FAA requirements often leave open the possibility for airlines to comply with the maintenance directives in other ways. In those instances, the FAA can agree to give the airlines more time to make the fixes.
American's Arpey said that in this case, the carrier applied for alternate means of compliance. The FAA did not grant American that option.
ABC News aviation consultant John Nance said the public should direct anger at the FAA instead of at American, saying faulty ties holding together the wiring underneath the planes' wheel well is not an immediate threat to public safety.
"This is like coming up to your car, finding you're 30 seconds over the line on the meter and the cop is writing you a ticket," Nance said.
But on Capitol Hill, Rep. James L. Oberstar, D-Minn., chairman of the House Transportation and Infrastructure Committee, said it's critical that airlines go strictly by the book.
"Those aircraft should have been inspected in due course in keeping with the airworthiness directives and they did not do that," Oberstar told ABC News. "Now they're making good on their requirement to maintain the margin of safety in aviation."