It's been the question on everyone's mind since Comair Flight 5191 crashed Sunday, killing 49 people: How could the plane end up on the wrong runway?
Federal officials won't rule on the official cause for months, but the crew must have missed several safeguards and potential warning signs as they prepared for takeoff and swept down the runway, according to pilots, aviation-safety experts and attorneys around the country.
"They went through several stop signs," said Ron Goldman, a Los Angeles lawyer with extensive experience in air-disaster litigation. "The safeguards are many."
Those include airport charts, runway lights and signs, as well as cockpit instruments, experts said.
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Flight 5191 was supposed to be on Runway 22, which is 7,000 feet long. Instead, the pilots attempted takeoff on Runway 26, which is only 3,500 feet long. The pilots apparently never realized they were on the wrong runway before the plane roared off the end of the strip at about 150 miles per hour, hitting a berm and then crashing and burning in a farm field.
The pilots would have started getting material to help them take off safely even before they boarded the aircraft, Goldman said -- a dispatch package with information on the flight and the airport, including a layout of runways and taxiways.
Once in the cockpit, the pilots would have listened to a recording with information such as weather conditions, which runway was in use and any abnormalities such as lights being out, said Charlie Monette, president of Aero-Tech, a flight school at Blue Grass Airport.
Monette said that when a plane leaves the gate at Blue Grass Airport, an air-traffic controller clears the pilot to taxi to Runway 22, then later clears the pilot to take off on Runway 22.
But the pilots on Flight 5191 would have known even earlier that they needed to be on 22, he said.
"The bottom line is there's only one runway here at the airport that's suitable for that type of aircraft," Monette said.
Investigators from the National Transportation Safety Board have said all the discussion between the control tower and the pilots on Flight 5191 was about Runway 22 -- the right one -- indicating the pilots thought they were on it.
But several clues showed they weren't, said pilots familiar with the airport.
For instance, Runway 26 is only half as wide as Runway 22, and there are no lights on the narrower, shorter strip. The center lights on 22, the correct runway, were out, but the side lights were on, an indicator that it was the active runway.
The plane attempted takeoff just after 6 a.m., so it was dark.
"Why would they line up on a runway that has no lights?" said Jim Burin, director of technical programs for the Flight Safety Foundation in Alexandria, Va.
There also are large signs on Runway 26, visible from a couple of miles out, to warn pilots that it is rated for visual flight rules only, said Jon Sisk, owner of Enhanced Flight Group in Lexington and a pilot. Runway 22 does not have those signs.
"That's another difference that the pilots should have noticed," he said.
Another potential red flag that Flight 5191 was on the wrong path: Workers recently repaved the main runway, leaving a dark, smooth strip of asphalt with freshly painted markings. By contrast, the surface of Runway 26 is uneven, rough and faded.
Another key safeguard, pilots and safety experts said, is that planes are equipped with a compass, and runway numbers correspond to headings on the compass. A reading of 260 degrees would have told the pilots they were lined up for takeoff on Runway 26, and not 22 as they should have been.
John Greaves, a former Comair pilot who estimated he flew in and out of the Lexington airport a hundred times in the 1980s, said that when lining up for takeoff it's routine to check that cockpit instruments are working and that the heading is correct for the runway.
"That should hit you right between the eyes," said Greaves, who is now an attorney in the same firm with Goldman. "Somebody should have caught that."
The pilot is ultimately responsible for the safe operation of the plane, said Joseph Galliker, president of Airline Safety Consultants International Inc., in Quebec.
"No matter how he got there, the last link in the whole event should have been him verifying that he's on the right runway," Galliker said.
The NTSB will look at a wide range of issues, including whether the pilots were fatigued; if the compass and other aircraft instruments were working properly; whether signs and lighting at the airport were adequate; and if the crew's familiarity with the airport played any role in the crash.
The airport had changed the taxiway layout during the recent major paving project. The NTSB said yesterday that both pilots had flown in and out of the airport several times the last two years, but not since the change in the taxiway configuration.
The pilot taxiing the plane to the takeoff point may have gotten confused, Greaves said.
Burin said plane crashes usually don't result from a single factor, but rather a chain of events. "If you take any one of them away, you don't have the accident," he said.
There was at least one more way to break that chain, said aviation experts and attorneys: The air-traffic controller who cleared Flight 5191 for takeoff could have watched to make sure the plane was on the right runway.
Scott Zoeckler, a 35-year veteran controller who retired two years ago after 27 years at Blue Grass Airport, said the controller's main role is to direct air traffic to make sure planes aren't getting in each others' way, not to make sure the pilots are doing their job correctly.
"If they don't understand what they're supposed to do, they need to call us and ask," Zoeckler said of pilots.
But Paul Czysz, professor emeritus of aerospace engineering at St. Louis University, said the controller does have a responsibility to make sure the plane is on the right runway.
"The tower didn't look and they didn't ask," Czysz said. "They (the pilots) thought they were in the right place and they were in the wrong place and the tower thought they knew and they didn't know. You can't let that happen."