COLDFOOT, AK, USA
N2566V
CESSNA 170
THE CERTIFICATED PRIVATE PILOT AND A PASSENGER WERE FLYING NORTHBOUND THROUGH A REMOTE MOUNTAIN PASS TOWARD RAPIDLY RISING TERRAIN. THEY WERE FOLLOWING A ROADWAY THAT PARALLELED THE TRANS-ALASKAN PIPELINE. BEFORE DEPARTING ON THE FLIGHT, THE PILOT WAS ADVISED BY A STATE TROOPER AND A LOCAL RESIDENT THAT FLIGHT THROUGH THE PASS WAS NOT ADVISED. THEY SUGGESTED AN ALTERNATIVE ROUTE OVER THE MOUNTAIN RANGE. THERE WERE NO WITNESSES TO THE ACCIDENT. THE WRECKAGE WAS OBSERVED BURNING ADJACENT TO THE ROADWAY ABOUT 4,500 FEET MEAN SEA LEVEL. WEATHER CONDITIONS AT THE PASS WERE REPORTED AS ABOUT 1,000 FEET OVERCAST, 15 TO 20 KNOTS OF WIND FROM THE NORTH, WITH ISOLATED RAIN AND SNOW SHOWERS MOVING THROUGH THE AREA.
History of the Flight On August 4, 1995, about 1900 Alaska daylight time, a wheel equipped Cessna 170, N2566V, collided with terrain in Atigun Pass, about 56 miles north of Coldfoot, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight to go hunting in the Brooks Range when the accident occured. The airplane, operated by the pilot, was destroyed by impact and postimpact fire. The certificated private pilot and the sole passenger received fatal injuries. Visual meteorological conditions prevailed in the area of the accident. The flight originated at the Coldfoot airport about 1830. The pilot departed Juneau, Alaska, on August 1, 1995, and flew to Fairbanks, Alaska. On August 4, 1995, at 0829, the pilot obtained a weather briefing via airplane radio from the Fairbanks Automated Flight Service Station (AFSS) for the area from Fairbanks to Livengood, Alaska, to Coldfoot. He stated that he was in the transient campground. At 1411, the pilot called the Kenai AFSS via telephone and filed a VFR flight plan from Manely Hot Springs, Alaska, via Livengood to Coldfoot. At 1605, the pilot cancelled his flight plan by radio with the Fairbanks AFSS. The pilot then transmitted on the AFSS frequency at 1606 that he was on a left downwind landing pattern for landing at Coldfoot. An Alaska State Trooper, Fish and Wildlife Division, reported that he talked with the pilot and passenger about 1630 after the airplane landed at Coldfoot. The pilot stated that he landed at Manley Hot Springs, Alaska, (137 miles south of Coldfoot) prior to continuing to Coldfoot and indicated to the trooper that he had been semi-lost and had to circumnavigate around numerous areas of low weather conditions. The pilot also told the trooper he was en route to the north side of the Brooks Range to meet a hunting party in an area known as Happy Valley, about 20 miles south of Sagwon, Alaska. The pilot was advised by the trooper that weather conditions in Atigun pass were not good, and he recommended an alternate route through Anaktuvuk Pass (64 miles northwest of Coldfoot) to traverse the mountain range. The fuel attendant at Coldfoot reported that he observed rain showers to the north and advised the pilot that it was snowing in Atigun Pass and discussed using Anaktuvuk Pass. After departure from Coldfoot about 1830, the airplane was observed to turn northbound toward Atigun Pass. About 1900, a witness observed smoke and the airplane burning along the side of the Dalton Highway that traverses the Brooks Range about 4,500 feet mean sea level (MSL). The accident occurred during the hours of daylight at lattitude 68 degrees, 07.30 minutes north and longitude 149 degrees, 29.45 minutes west. Crew Information The pilot held a private pilot certificate with airplane single-engine land and single-engine sea ratings. The most recent third-class medical certificate was issued to the pilot on August 12, 1993, and contained the limitation that the pilot must have available glasses for near vision. No personal flight records were located for the pilot and the aeronautical experience listed on page 3 of this report was obtained from a review of the Federal Aviation Administration's (FAA) records on file in the Airman and Medical Records Center located in Oklahoma City. On the pilot's application for medical certificate on August 12, 1993, the pilot indicated that his total aeronautical experience consisted of 200 hours, with zero flight time accrued in the previous 6 months. Aircraft Information No airframe or engine maintenance records were located for the accident airplane. Fueling records at Coldfoot established that the pilot purchased 18 gallons of 100LL octane aviation fuel before departing on the accident flight. The fuel truck operator reported that although the pilot paid for 18 gallons, the airplane only required 15 gallons to fill both fuel tanks. A review of the airplane manufacturer's performance data revealed that at a density altitude of 5,000 feet, the best climb speed is 82 MPH, which results in a rate of climb of 485 feet per minute at gross weight. Calculation of the above data revealed a 355 foot per minute rate of climb per mile. Meteorological Information The pilot obtained a weather briefing from the Fairbanks AFSS on August 4, 1995, at 0829 from Fairbanks via Livengood to Coldfoot. The briefing included precautions on the entire route of flight for mountain obscuration and IFR conditions. VFR flight was not recommended. The briefer could not provide any weather information for Livengood or Coldfoot, but provided a 0734 surface weather observation from Chandalar Lake, Alaska, (46 miles southeast of the accident site). The weather condition were reported as: Sky condition and ceiling, 1,000 feet scattered, estimated 2,300 feet overcast; visibility, 15 miles; temperature, 45 degrees F; dew point, 43 degrees F; wind, calm; altimeter, 29.45 inHg. The AFSS briefer provided information about the area forecast that was calling for ceilings of 5,000 feet broken to scattered clouds, occasionally 3,000 feet broken with light rain showers with localized ceilings of 1,500 feet overcast; visibility, 3 to 5 miles in light rain showers and fog, and convective activity later in the afternoon. The forecast for Anaktuvuk and Atigun passes called for marginal VFR due to ceilings with IFR due to ceilings and fog in the northern ends. The pilot inquired about the weather conditions for the rest of the day. The briefer replied that: "...conditions uh are going to be uh just about the same all day long uh maybe a slight decrease in the weather." An automated weather observation system (AWOS) at Anaktuvuk Pass, is located 50 nautical miles west of the accident site. At 1955, a surface observation was reporting in part: Sky condition and ceiling, 600 feet scattered, measured ceiling 2,800 feet broken, 3,800 feet overcast; visibility, 10 miles; temperature, 38 degrees F; dew point, 31 degrees F; wind, 050 degrees at 12 knots, gust to 17 knots; altimeter, 29.52 inHg. Witnesses in the area of the accident between 1900 and 2000 reported that weather conditions in the pass consisted of broken to overcast sky conditions that were about 1,000 feet above the surrounding terrain. Visibility was reported as about 10 miles with light rain showers and light snow falling in widely scattered and isolated areas. The wind conditions were about 10 to 20 knots from the north. Communications The pilot communicated with the Fairbanks AFSS via radio to obtain a weather briefing and to close his flight plan to Coldfoot. A transcript of the air to ground communications between the pilot and Fairbanks AFSS is included in this report. In addition, the pilot filed a VFR flight plan by telephone from Manely Hot Springs to Coldfoot with the Kenai AFSS. The multi-channel recorder at the Kenai AFSS was out of service and no transcript was available. FAA personnel reported that all services provided by the Kenai AFSS were normal and there were no pertinent transmissions. Wreckage and Impact Information The National Transportation Safety Board investigator-in-charge and an FAA inspector examined the airplane wreckage at the accident site on August 5, 1995. The terrain in the area from Manley Hot Springs, north to the area of the accident consists of continuous rolling hills and valleys with the Yukon River being the most conspicuous. The most prominent man-made features in the area are the Trans Alaska pipeline and the Dalton Highway that parallels the pipeline. The accident site was located in one of several remote mountain passes that cross the Brooks Range which separates the central interior of the state from the Arctic region. The terrain from Coldfoot to Atigun Pass is a wide valley that rises toward the mountain range. At the south end of the pass, the elevation is about 3,500 feet msl. The distance from the beginning of the pass to the accident site is about 1.5 miles. The terrain rises at a rate of 666 feet per mile. The airplane was located on about a 25 degree slope, about 200 yards below the elevation of the Dalton Highway, about 4,500 feet msl. The terrain around the accident site consisted of boulders and tundra, covered with about 2 inches of snow. The nose of the airplane was oriented on a magnetic heading of 018 degrees. (All heading/bearings noted in this report are oriented toward magnetic north.) All of the airplane's major components were found at the main wreckage area. The left wing, oriented upslope, was fire damaged with melting of the wing fabric, from the inboard end, outboard to about mid-span. The leading edge exhibited slight spanwise lower edge crushing from the inboard end to about mid-span. At that point, the wing displayed a semi-circular aft and upward crush and bend, aft to the forward spar. The outboard portion of the wing was not significantly damaged. Examination of the left wing position light bulb revealed that the filament was fractured in several pieces from the support posts. The aileron and flap remained attached to the wing. The wing lift struts remained attached to their respective wing and fuselage attach points. The left wing fuel tank was located separated from the wing, lying to the rear of the right wing aileron. It exhibited fire damage and inward crushing. A small portion of fuel was contained within the folds of the tank material. The right wing exhibited extensive fire damage and melting of the wing fabric, from the inboard end to the tip. It was displaced aft about 45 degrees from the left wing. The leading edge displayed spanwise lower edge crushing from the inboard end to about 3 feet outboard of the wing lift strut attach point. At that point, the wing exhibited an upward buckling and aft crushing of the leading edge, aft to the forward spar that was bent in a slight "S" shape. The aileron remained attached to the wing. The flap assembly separated from the wing attach points and was located lying adjacent to the aileron. The lift strut remained attached to the wing and its lower fuselage attach point. The right wing fuel tank remained attached to the wing and was extensivly destroyed by fire. The fuselage, including the inboard ends of the wing spars and spar carry-through, was destroyed by fire. The left landing gear strut was displaced aft along the left side of the wreckage. The right landing gear strut was displaced aft and inboard (to the left) to about the center of the wreckage. The empennage was undamaged from about 10 inches forward of the vertical stabilizer attach point. The rudder, elevator, and trim tab remained attached to the empennage. Examination of the rear position light bulb revealed that the filament was intact and tightly coiled. The tail wheel assembly appeared undamaged. The pilot's (left side) door was located separated from the fuselage about 40 feet south of the fuselage. The flight control surfaces remained connected to their respective attach points. Due to impact and postimpact fire damage, the flight controls could not be operated by their respective control mechanisms. Flight control continuity was established via the cables to the cockpit. The postcrash fire incinerated the cabin/cockpit area. Two seat belt buckles with the latch portion still retained in the buckles were located in the wreckage. The face of the airspeed indicator was located in the instrument panel debris separated from its case. The needle was pointing to 120 MPH. The rest of the instrument panel was destroyed. The propeller assembly remained connected to the engine crankshaft. One propeller blade exhibited leading edge gouging, chordwise scratching, "S" bending and torsional twisting. The second blade was curved aft about 30 degrees and exhibited torsional twisting. The outboard end of the blade was separated about 8 inches inboard from the tip. It exhibited heavy leading edge gouging and chordwise scratching on the cambered side of the blade. The engine was canted about 30 degrees to the right from the longitudinal axis of the airplane. The engine was bent upward about 45 degrees from the vertical axis of the firewall. The firewall was crushed forward against the aft end of the engine. The front nose portion of the engine case was fractured, exposing the crankshaft. The engine cowling was crushed in an upward direction against the engine. Fire damage was evident to the underside and rear accessory portion of the engine. The engine sump was melted, exposing the interior of the engine. The magnetos were destroyed by fire. Examination of the upper number 6 and number 4 cylinder spark plugs revealed that the massive electrodes were dry and exhibited a blackened appearance. Medical and Pathological Information A postmortem examination of the pilot was conducted by the State of Alaska, Office of the State Medical Examiner, 5700 E. Tudor, Anchorage, Alaska, on August 7, 1995. A toxicological examination conducted by the medical examiner noted that the pilot had an ethanol level of 16 mg/dl in the blood. The examiner commented that:..."The amount of ethanol present in the blood of the decedent is insignificant and may represent postmortem production of ethanol by microorganisms." The medical examiner elected to not submit samples for a microscopic examination of the pilot. Additional Information The Safety Board did not take custody of the wreckage. No parts or components were retained by the Safety Board.
THE PILOT'S FAILURE TO MAINTAIN ADEQUATE DISTANCE AND/OR ALTITUDE FROM TERRAIN. RISING MOUNTAINOUS TERRAIN AND DOWNDRAFTS ASSOCIATED WITH UNFAVORABLE WIND CONDITIONS WERE FACTORS IN THE ACCIDENT.
Source: NTSB Aviation Accident Database
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