After putting in 13,000 man hours of investigation over 11 months and reviewing more than 1,000 pages of evidence, federal investigators concluded that Comair Flight 5191 crashed because of mistakes made by the pilots.
But investigators still could not answer the question that has frustrated them since Aug. 27, the day of the crash: How did two experienced pilots, navigating a simple, "straightforward" airport, take off from the wrong runway?
And why did they take off from an unlit runway -- a black hole -- asked National Transportation Safety Board chairman Mark V. Rosenker.
"To try to get into the minds of operators, of pilots -- you can't do it," Rosenker said after the hearing.
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The NTSB attempted to delve into the minds of pilots Jeffrey Clay and James Polehinke to find answers in the crash that killed 49 people near Blue Grass Airport. Polehinke was the only survivor.
After a daylong hearing that looked at everything from air traffic control to taxiway markings, the NTSB cited two major errors by the plane's pilot and co-pilot as the causes of the crash: their failure to use cues and aids to identify the aircraft's location, and their failure to verify that the commuter plane was on the correct runway before takeoff.
The five-member board identified two contributing factors to the crash: the crew's distracting cockpit conversation about work, family and other topics; and the Federal Aviation Administration's failure to require that all pilots be cleared by air traffic controllers before they cross a runway.
At 6:05 a.m. on Aug. 27, in dark but clear conditions, the 50-seat regional jet weighing 50,000 pounds took off from the shorter of Blue Grass's two runways, Runway 26, which was far too short for a plane that size. It was supposed to take off from Runway 22, which is 7,000 feet long.
Many questions remained yesterday as the board delved into what NTSB member Debbie Hersman described as "the briar patch of human behavior." Hersman was the NTSB member on the scene of the Lexington crash.
"It did not take long for all of us to realize that, no matter how many people we interviewed, no matter how many documents we reviewed, no matter how much evidence we collected, the accident would offer up no easy explanations for us," Hersman said. "No simple solutions. There would be no moment where we could point to one thing and say, 'Aha, that is what caused this accident.'"
Hersman described the Comair crash as the "most searing" she's been involved in -- because of the loss of life and because there was no single, clear cause, such as a mechanical problem.
The board also considered a staff recommendation to include a third contributing factor: the air traffic controller's performance of an administrative task not directly related to flight safety. However, the board voted, 3-2, to remove that factor from the official listing of causes.
Hersman and member Kitty Higgins, who voted to keep the controller as a contributing factor, said they will file concurring opinions.
After ruling on the cause, the NTSB made several safety recommendations to the Federal Aviation Administration. Those included requiring pilots and co-pilots to cross-check and confirm that they are on the correct runway; requiring that cockpits be fitted with electronic maps or displays that would alert pilots if they are on the wrong taxiway or runway; enhancing taxiway markings; and telling air traffic controllers to refrain from performing administrative functions while they are supposed to be monitoring the safety of aircraft.
The board reiterated some earlier recommendations, including additional guidance for using unlit runways and urging the FAA to deal with issues related to fatigue among air traffic controllers.
Board members expressed frustration at the FAA's failure to enact prior recommendations, particularly those dealing with runway issues.
Throughout the hearing, board members discussed the several cues that the pilots missed that should have warned them they were on the wrong, too-short runway, and how they chatted about irrelevancies.
"The appropriate and available cues were there to make the decisions that day," NTSB member Steven Chealander said. "The flight crew didn't do their job. They didn't take the responsibility serious enough to do the job using those cues and they took off from the wrong runway."
The biggest cue of all was the stark contrast between unlit Runway 26 and Runway 22, which was "lit up like a Christmas tree," Rosenker said.
"It didn't appear that their head was fully in the game," he told reporters.
But systemic failures also played a role, Hersman said. She pointed out that Clay and Polehinke had potentially confusing charts and signs, were not given notices of a taxiway closing, were looking at a reconstructed taxiway and that lights were out in at various times and various places.
"It's very clear to us this crew made a mistake, but the question is what enabled them to make this mistake," Hersman said.
"The aviation system is supposed to have redundancy," Hersman said, outlining the omitted notices and reading an extensive warning provided after the crash by another airline. "It's just a shame this information wasn't there before the accident."
The NTSB investigator-in-charge, Joseph Sedor, said that the crew had illuminated signs, blue taxiway signs, runway markings, barricades, and a very dark forward view instead of the well-lighted runway they should have expected. And there were no indications crew members thought they were in the wrong place.
In fact, a minute after the plane began taxiing out, "the crew engaged in 40 seconds of non-pertinent conversation," he said. Then, as the plane waited for 50 seconds before turning to take off, crew members had multiple cues they were in the wrong place.
"There is not one single bit of information that the staff looked at that could have caused this accident, except for the non-pertinent conversation," Sedor said.
On the flight's voice recorder, the pilots never appeared confused. It was a classic example of confirmation bias, the act of only seeing evidence supporting their preconceptions, investigators said.
The pilots missed more than a half-dozen cues and aids: their heading indicator, which corresponds with runway numbers; the airport diagram, which showed that they had to cross over Runway 26; the lack of edge lights on the shorter runway, and the fact it was half as wide as the primary runway; the clearly visible sign showing they were turning onto Runway 26.
The pilots could have talked to the controller if they were confused, said Evan Byrne, who led the team investigating human performance. They were not pressed for time.
One condition that could have reinforced confirmation bias is that several edge lights on the right side of runway 22 were out when Polehinke flew in two nights before, Hersman said. She noted that a plane that was to land in Lexington that night turned around and landed at the Northern Kentucky-Cincinnati airport since those edge lights, and the center-line lights, were out.
The lights, which had been out because of electrical problems, were running the morning of the crash.
"Things were not as they were normally at this airport," Hersman said. "It was not the perfect situation. It was something less than what we require on a regular basis."
The board also debated whether the air traffic controller should have been able to stop the accident. Or whether having two controllers, as the FAA had mandated, would have affected the outcome.
"I think this accident is all about complacency," Higgins said. "The crew was complacent, and I would argue the controller was complacent."
According to the investigators, controller Christopher Damron had two chances to alert the pilots that they were in the wrong place: a window of opportunity while the plane sat for 50 seconds at the wrong "hold short" line, and a second window of 28 seconds when the plane was moving down the wrong runway.
"We felt that, if someone was really thinking about contingencies, they might have been able to notice something. That's why we call it a window of opportunity," said Bill Bramble, human performance group chairman. "We are just not convinced it would have changed the outcome."
Hersman, Higgins and other investigators weren't so sure.
"I know the controller did not fly the airplane down the wrong runway, but he did not do anything to prevent it either," said Sandy Rowlett, an NTSB investigator.
Hersman outlined several places where the control system broke down: The controller didn't record a crucial notice that a taxiway was closed; there was oral but not written guidance from the FAA on having two staffers in the tower; guidance that wasn't followed; and the controller was fatigued "because his schedule defies everything that we know about fatigue." The controller had been awake for 22 hours of the 24 hours before the crash.
And, Hersman said, the controller said it wasn't his practice to watch the planes take off.
The crew did not have several local notices (known as Notices to Airmen, or NOTAMs) that morning. The missing NOTAMs included one about the taxiway that had been closed because of a major runway construction project. The airport faxed those notices to Comair, but they weren't given to the crew.
At the same time, the local notices should have been included on the ATIS, a radio frequency that pilots listen to for pre-recorded information about changes at the airport. The local notice information had been on the ATIS in days before the crash, but it wasn't there Aug. 27. NTSB investigators said it's unclear why the air traffic controller did not record the local notice information on the ATIS that morning.
Finally, the runway/taxiway charts being used by the crew were out of date and did not accurately reflect changes on the ground because of construction.
"There were numerous failures, numerous holes, and we've got to address the system," Hersman said. "I guarantee you this controller will never make these mistakes again. The challenge is to make sure no other controller makes these mistakes."
Probable causes of the crash:
The flight crew's failure to use cues and aids to identify the aircraft's location.
The flight crew's failure to cross-check and verify that the airplane was on the correct runway before takeoff.
The FAA's failure to require that planes get clearance from air traffic control before they cross a runway.