Aniak, AK, USA
N351AS
Learjet 35A
The flightcrew of a turbojet airplane were landing during dark night VFR conditions at the conclusion of an instrument flight rules (IFR) cross-country aeromedical positioning flight. The captain said he broke out of the cloud base about 1,200 feet msl, 7 miles from the runway. He said he was holding about 15 to 20 degrees of left crab to remain aligned with the runway centerline, and he felt a strong crosswind over the runway threshold. During the landing flare, the left wingtip fuel tank contacted the runway. The captain applied full right aileron and full right rudder, and the airplane touched down on the centerline. After parking, an inspection of the left wingtip fuel tank revealed scraping and flattening of about the aft third of the underside of the fuel tank. The upper surface of the wing, inboard from the tip tank, was wrinkled. The automated weather observing system (AWOS) was reporting, in part: Wind, 270 degrees at 5 knots; visibility, 9 statute miles; clouds and sky condition, 1,200 feet overcast. The FAA Facility Directory/Alaska Supplement notes that "Because of natural obstructions, the AWOS-3 wind may be unrepresentative of runway wind conditions." The captain indicated that the landing approach speed was flown with additional airspeed to compensate for the wind conditions, and he noted that he could only assume that windshear contributed to the accident.
On February 21, 2008, about 1950 Alaska Standard time, a Learjet 35A airplane, N351AS, received substantial damage during the landing flare/touchdown at the Aniak Airport, Aniak, Alaska. The airplane was being operated as an instrument flight rules (IFR) cross-country aeromedical positioning flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by Chipola Aviation Inc., Panama City, Florida. The captain, an airline transport certificated pilot, the first officer, a commercial certificated pilot, and three medical crewmembers, were not injured. Dark night visual meteorological conditions prevailed, and an IFR flight plan was filed. The flight originated at the Ted Stevens Anchorage International Airport, Anchorage, Alaska, about 1905. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on February 22, the pilot, who is the director of operations for the operator, reported that the flight was positioning to Aniak to pick up a patient. He said he was on the GPS approach for landing on runway 28, and broke out of the cloud base about 1,200 feet msl, 7 miles from the runway. He was holding about 15 to 20 degrees of left crab to remain aligned with the runway centerline. The automated weather observing system (AWOS) was reporting the winds as 260 degrees at 4 knots. He experienced light to moderate turbulence during the approach, but no turbulence from about 1,000 to 100 feet msl. He said he felt a strong crosswind over the runway threshold, and during the flare, the left wingtip fuel tank contacted the runway. He applied full right aileron and full right rudder, and the airplane touched down on the centerline. After parking, an inspection of the left wingtip fuel tank revealed scraping and flattening of about the aft third of the underside of the tank. The upper surface of the wing, inboard from the tip tank, was wrinkled. In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the captain, he reported that during the approach, he utilized a landing approach (Vref) speed of 123 knots. He said that the final approach speed was Vref, plus 10 knots. The captain stated that he recalled the first officer reporting "Vref plus 5 [knots]," just before the left wingtip struck the runway. The FAA's airport facility directory/Alaska Supplement, notes that Aniak, elevation 88 feet msl, has a hard-surfaced runway that is 6,000 feet long, and 150 feet wide. The airport is equipped with approach lights, high intensity runway lights, sequenced flashing lights, and visual approach slope indicator. In the "Recommendation, How could this accident have been prevented" section of the NTSB Form 6120.1, the captain indicated that he thought that he "must be more cautious of windshear conditions," and said that he could "only assume that windshear contributed to this incident." At 1956, an automated weather observing system (AWOS) at Aniak was reporting, in part: Wind, 270 degrees at 5 knots; visibility, 9 statute miles; clouds and sky condition, 1,200 feet overcast; temperature, 9 degrees F; dew point, 4 degrees F; altimeter, 29.40 inHg. The FAA Facility Directory/Alaska Supplement notes that "Because of natural obstructions, the AWOS-3 wind may be unrepresentative of runway wind conditions."
The captain's inadequate compensation for wind conditions during the landing flare/touchdown. Contributing to the accident were a crosswind and windshear.
Source: NTSB Aviation Accident Database
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