Aviation Accident Summaries

Aviation Accident Summary ANC03LA062

GOODNEWS, AK, USA

Aircraft #1

N512FS

Swearingen SA-226T

Analysis

The captain, the non-flying pilot seated in the right seat, and the first officer, the flying pilot seated in the left seat, were landing a twin engine turboprop airplane at a remote airport at the conclusion of an air taxi flight. The flight was conducted on an IFR flight plan to a nearby airport, and then proceeded VFR, 9.5 miles to the destination airport that has a gravel surface runway, 2,835 feet long and 80 feet wide. The crew reported that a stabilized landing approach was conducted to runway 05 at a reference (REF) airspeed plus 10 knots, with a 5 knot crosswind. The copilot indicated that during the landing, the airplane encountered a severe downdraft and contacted the ground about 100 feet short of the runway threshold. The captain indicated a wind shear of 8 knots was encountered. The closest official weather observation station is located 32 nautical miles south of the accident site. It was reporting, in part: Wind, 180 degrees (true) at 16 knots, gusts to 26 knots. A passenger, who stated he was a meteorologist by training, reported the wind during the landing approach was a direct right crosswind between 12 and 15 knots, with gusts to 20 knots.

Factual Information

On June 28, 2003, about 1140 Alaska daylight time, a Swearingen SA-226T airplane, N512FS, sustained substantial damage when it collided with terrain short of the runway threshold during landing at Goodnews, Alaska. The airplane was operated by F S Air Service Inc., Anchorage, Alaska, as an on-demand passenger flight under Title 14, CFR Part 135, when the accident occurred. The captain, first officer, and 6 passengers, were not injured. Two other passengers received minor injuries. Visual meteorological conditions prevailed. VFR company flight following procedures were in effect. The flight originated at the Ted Stevens Anchorage International Airport, Anchorage, at 0830. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on June 28, the director of operations for the operator reported that the flight operated on an instrument flight plan from Anchorage to Platinum, Alaska, and then proceeded VFR for the 9.5 mile flight from Platinum to Goodnews. The flight crew told the director of operations that they were established on the approach to runway 05 when the airplane encountered a downdraft and descended. The airplane collided with the ground about 100 feet short of the runway threshold, bounced onto the runway, and then slid off the right edge of the runway. The airplane received damage to the fuselage and wings. A review of recorded radio transmissions between the Federal Aviation Administration's Air Route Traffic Control Center (ARTCC) and the flight crew revealed that while en route to Platinum, the crew requested weather information for Togiak, Alaska, and Platinum. The crew was told that the weather conditions in Togiak were, in part: wind, 160 degrees at 11 knots; visibility, 10 statute miles; sky condition, 10,000 feet overcast. The crew was advised that a weather report for Platinum was not available. As the flight progressed toward Platinum, the crew requested and received an approach clearance for the GPS runway 13 approach to Platinum. The crew then reported that they were in VMC conditions and would like to cancel their IFR flight plan. In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1) submitted by the operator, the flight crew reported that the captain was seated in the right seat and was the non-flying pilot. The copilot was seated in the left seat and was the flying pilot. The captain stated that they overflew the runway, noted the wind direction and velocity, and entered a downwind pattern for runway 05. The captain said full flaps were selected with a reference (REF) airspeed, plus 10 knots, with a stabilized approach. During the final seconds prior to landing, the captain reported a wind shear of about 8 knots, accompanied with a downdraft. The airplane contacted the ground prior to the threshold. The copilot, who was the flying pilot, reported that the airplane was on a stable approach with an airspeed of REF, plus 10 knots, with a 5 knot crosswind. About 30 feet above the runway, the copilot said the airplane sank, having encountered severe wind shear, and struck the ground in the runway turn-around area. On October 6, 2003, the NTSB IIC received a telephone call from one of the passengers. He related that he was a meteorologist by training, he had received pilot training in the past, and he had flown to Goodnews on numerous occasions, including flights in the accident airplane. The passenger described an overcast ceiling of about 1,200 feet, and he stated that during the landing approach, the wind conditions consisted of a direct right crosswind between 12 and 15 knots, with gusts to 20 knots. He said that about 20 feet above the ground, the airplane suddenly descended and collided with the edge of the runway area. The passenger stated that the seat configuration, from the front to the rear of the airplane, consisted of 4 inward facing seats along the left side of the airplane, then a forward facing seat at the left rear of the cabin. The right side of the cabin had an aft facing seat, then two forward facing seats. The passenger also indicated that he and another passenger seated on the left side of the airplane, received injuries when struck by the two forward facing seats from the right side of the cabin that became dislodged during the crash. The Airport/Facility Directory/Alaska Supplement for Goodnews, states, in part: "Remarks - Unattended. Caution: Runway condition not monitored, recommend visual inspection prior to use. Birds on and in vicinity of the airport. Road crosses midpoint of runway 05-23. Windsock may give erroneous indications in low wind conditions. Runway 05-23 slopes uphill 1.0 percent to the east end." Runway 05 is a gravel surface runway, 2,835 feet long and 80 feet wide. The airport elevation is 15 feet msl. The Airport/Facility Directory/Alaska Supplement for Platinum, lists the airport identifier as either PTU or PAPM. The airport facility directory also indicated that the airport has an automated weather observation system (AWOS-3) with a dial-in phone number and a radio frequency. In the Pilot/Operator Aircraft Accident Report submitted by the operator, the weather information provided by the operator indicated the following: Source of weather information, commercial weather service; method of briefing, teletype; briefing type, standard; weather facility, PTM; observation time, 1000; distance from accident site, 15 nautical miles; direction from accident site, southwest; temperature, 9 degrees C; dew point, 8 degrees C; sky condition, 3,000 feet broken; wind, 090 degrees (true) at 10 knots; light precipitation. The closest offical National Weather Service observation station to the accident site is Cape Newenham Long Range Radar Station (LRRS), Alaska, which is located 32 nautical miles south of the accident site. At 1155, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind, 180 degrees (true) at 16 knots, gusts to 26 knots; visibility, 5 statute miles; clouds and sky condition, 1,000 feet broken, 1,700 feet overcast; temperature, 46 degrees F; dew point, 45 degrees F; altimeter, 30.02 inHg.

Probable Cause and Findings

The flight crew's inadequate evaluation of the weather conditions, which resulted in their inadequate compensation for the wind conditions, and subsequent undershoot. A contributing factor in the accident was a downdraft.

 

Source: NTSB Aviation Accident Database

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