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Pre-takeoff shortcut proves deadlyPre-takeoff shortcut proves deadly

(NYC08FA218)(NYC08FA218)

By David Kenny

Flying the same aircraft frequently helps a pilot develop a flow. Running through the same steps in the same sequence over and over imprints them on memory. Checklists become references rather than instructions. If the pilot is in a hurry, though, the flow can be disrupted. Rushing to beat a clearance void time or make up for earlier delays increases the risk of forgetting something—maybe something crucial.

Just before 10 a.m. on June 18, 2008, the pilot of a DHC-6 Twin Otter contacted air traffic control at Barnstable Municipal Airport in Hyannis, Mass., to request a taxi clearance. Weather was good visual meteorological conditions, with 10 miles visibility and clear skies, but an instrument flight plan was on file for the Part 135 cargo flight to Nantucket. Departure was scheduled for 9 a.m., but according to the airplane’s operator, delays were common because cargo often arrived late. At 10 a.m. sharp, the airplane was cleared for takeoff.

The flight lasted less than a minute. A witness outside the fence near the arrival end of the runway saw the airplane lift off after a very short takeoff roll—perhaps 100 yards—and immediately bank hard to the left. The bank was so steep, and the airplane’s altitude so low, that the witness thought it might drag a wingtip. It disappeared behind a grove of trees shortly before impact. The debris field began just 1,100 feet from the runway threshold. The pilot was killed in the crash.

The 43-year-old pilot held multiengine air transport pilot and single-engine commercial privileges and a first-class medical certificate. He had logged more than 3,600 hours of flight time, more than half of it in multiengine airplanes, with 99 in the DHC-6. Winds were 9 knots down the runway, and the airplane was lightly loaded with one pilot and 208 pounds of cargo. Calculations after the accident confirmed that its center of gravity was within limits. So what happened?

The airplane hit nose-low, crushing the fuselage back to the cockpit bulkhead and the outer leading edges of both wings. The wings remained attached only by the control cables, but continuity was established between the cockpit and all flight controls. Examination of the engines found no indication of malfunction prior to impact, and the pattern of damage to the propellers was consistent with both engines producing full power when they struck the ground.

The control column was found separated from its mount—with the upper control lock still installed. Three earlier Twin Otter accidents (in 1979, 1980, and 1988) had each led de Havilland Canada to issue service bulletins requiring modifications of the control locks to reduce the risk of taking off with one in place. Transport Canada issued an airworthiness directive in 1990 requiring compliance with the most recent of these, but the FAA had not followed suit. None of the service bulletins had been performed on the accident airplane. (After this accident, the FAA issued airworthiness directive 2008-CE-046-AD, requiring compliance with the 1988 service bulletin by June 30, 2009.)

Time pressures are a fact of life, but the pre-takeoff checklist isn’t the best place to shave seconds. Three essential checks should be made before every departure, no matter how rushed:

  • Engine configuration correct. Three common mistakes can be fatal: leaving the mixture ground-leaned near sea level, setting it full rich at higher elevations, and leaving the fuel selector on a near-empty tank.
  • Flight controls free and correct. Verifying this would have allowed a routine 27-nm flight to proceed routinely.
  • Belts and harnesses secure. The NTSB report mentions that “The pilot’s four-point restraint was found unfastened, and no deformation of the buckles, mounts, retraction mechanism, or belt webbing was noted.” However poor the chances of surviving this accident, going unbuckled didn’t help.

Together, all three might cost 30 seconds. Take the time.