Friday, February 1, 2008
Asking the eternal, unanswerable question
|In every accident, there’s a chain of events or conditions leading to the outcome. Break one of the links in the chain, and the accident can be avoided, at least in theory. The individual links leading to the crash of Comair flight 5191 at Lexington, Ky., on August 27, 2006, aren’t big ones like an engine failing or running out of fuel. The NTSB’s final report indicates plenty of opportunities to change the course of events. There’s almost a compulsion to ask over and over again, “what if?”|
The controller replied, “Comair one ninety-one, Lexington clearance. Cleared to Atlanta Airport via Bowling Green, ERLIN TWO arrival. Maintain 6,000, expected flight level two seven zero one zero minutes after departure. Departure’s one two zero point seven five. Squawk six six four one.” The first officer responded, “Okay, got Bowling Green, missed the other part. Six thousand, twenty point seven five, six six four one.” The controller advised, “Comair one ninety one, it’s ERLIN TWO, Echo, Romeo, Lima, India, November Two arrival.” What if missing part of the clearance had sharpened the first officer’s focus?
The first officer accepted the captain’s offer to act as flying pilot to Atlanta. While doing the takeoff briefing, the first officer asked which runway they’d be using (specifically, whether it was runway 24). The captain replied, “It’s two two.” The first officer continued with the briefing, which included three additional references to runway 22. He noted that the runway end identifier lights were out: “Came in the other night like [this]…lights are out all over the place.” A few minutes later, the first officer called for the first two items on the “before starting engines” checklist. The captain reminded him that they had already completed the checklist. The first officer replied, “We did?” What if the captain had asked the first officer if he was sure he wanted to handle the flying duties?
At 6, the engines were started, and the captain said the airplane was ready to push back from the gate. At 6:02, the first officer radioed the tower controller that they were ready to taxi and they had ATIS information alpha. The controller said, “Comair one ninety-one, taxi to runway two two. Altimeter three zero zero zero and the winds are two zero zero at eight.” The first officer acknowledged, “Triple three zero and taxi two two, Comair one ninety-one.” The clearance authorized them to cross runway 26 in order to reach the hold-short line for runway 22. What if the clearance had required them to stop at runway 26 before receiving a specific clearance to cross it and continue to runway 22?
The captain began taxiing at 6:02:17. At the same time, a SkyWest flight was taking off from runway 22. The captain then called for the taxi checklist. Taxi time was two and one-half minutes. According to the CVR, the captain and first officer spent 40 seconds discussing other pilots. What if they had been discussing progress along the taxi route instead?
The airplane continued along taxiway A; at 6:04:01, the first officer began the pretakeoff checklist, stating, “We got runway two two out of Lexington up to six [thousand feet].” The hold-short line for runway 26 was on taxiway A. To reach runway 22, aircraft had to cross runway 26 and continue on the balance of taxiway A. But the portion of the taxiway beyond runway 26 leading to runway 22 had been closed as part of a reconstruction project. To reach runway 22, aircraft now had to make a left turn onto runway 26 and continue across onto what had been taxiway A5, but was renamed taxiway A. On the morning of the accident, the hold-short line for runway 22 was on the former taxiway A5. The commercial chart given to the flight crew was dated January 2006. It showed neither that taxiway A5 had been redesignated as taxiway A nor that the segment of the original taxiway A leading to runway 22 had been closed. A local NOTAM advised that taxiway A was closed north of runway 26. The NOTAM, however, wasn’t in the dispatch package given to the flight crew. What if the flight crew had the NOTAM and a chart updated with details on the construction project?
At 6:04:33, the captain stopped the airplane at the hold-short line for runway 26, instead of continuing past it along the new taxiway A to the hold-short line for runway 22. The first officer then invited the passengers to “enjoy the flight” and asked that the cabin be prepped for takeoff.
The controller on duty in the tower had just finished getting the departure clearance for flight 5191 and coordinating a heading change for the SkyWest flight that had just departed. The controller then spent eight seconds vectoring an American Eagle flight. Handling the SkyWest and American Eagle flights required the controller to pay attention to his radar screen. At 6:05:15, the first officer radioed that they were ready for takeoff. The first officer didn’t mention the runway. Three seconds later, the controller radioed, “Comair one ninety-one, Lexington tower, fly runway heading, cleared for takeoff.” Again, there was no mention of the runway designation. At 6:05:40, the controller handed off the American Eagle flight to Indianapolis Center. About one second later, Comair 5191 began taxiing past the hold-short line and turning onto runway 26. What if the runway designation had been mentioned? Would that have prompted the Comair flight crew to cross-check their directional instruments?
At 6:05:58, the captain told the first officer that the airplane was “all yours.” The airplane was on a magnetic heading of 266 degrees, the heading for runway 26.
The controller hadn’t noticed that the flight crew had stopped the airplane at the hold-short line for the wrong runway. He said he was paying more attention to his radar responsibilities than to the responsibilities of the local tower-controller position. He reported that he didn’t monitor the airplane’s takeoff roll. Instead, he turned his attention to an administrative task dealing with flight progress strips. What if the controller had spent more time looking out of the tower cab window?
At 6:06:16, the first officer, apparently referring to the lack of runway edge lights, said, “[That] is weird with no lights,” and two seconds later the captain responded, “Yeah.” At 6:06:24, the captain called, “100 knots”; the first officer replied, “checks.” Seven seconds later, the captain called, “V one, rotate,” followed by “whoa.” The airplane was at 131 knots, about 11 knots below calculated rotation speed. The control columns were pulled all the way back, and the plane’s nose went up at a rate of 10 degrees per second. The airplane struck a four-foot-tall earthen berm 265 feet from the end of runway 26. It then became airborne, rising to no more than 20 feet above the ground, and hit a tree 900 feet from the end of the runway. The captain, flight attendant and all 47 passengers were killed. The first officer survived.
The NTSB determined that the accident’s probable cause was the flight crew’s failure to use available cues and aids to identify the airplane’s location on the airport surface during taxi, and their failure to cross-check and verify that the airplane was on the correct runway. Also contributing were the flight crew’s nonpertinent conversation during taxi, which resulted in a loss of situational awareness, and the FAA’s failure to require that all runway crossings be authorized only by specific air-traffic-control clearances.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.
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