SEA93FA206
SEA93FA206

HISTORY OF FLIGHT

On September 20, 1993, approximately 1200 Pacific daylight time (PDT), a Cessna 180B, N985DB, impacted the terrain about four miles northeast of Mullan, Idaho. The private pilot, who was the sole occupant of the aircraft, received fatal injuries and the aircraft was destroyed. The FAR Part 91 flight, which was en route to Hermiston, Oregon, departed Missoula Regional Airport, Missoula, Montana about one hour prior to the crash. The aircraft was operating in instrument meteorological conditions at the time of the accident, and no flight plan had been filed. There was no report of an ELT activation.

According to witnesses, on the day of the flight the pilot intended to fly to Hermiston, Oregon, where he was planning to perform aircraft maintenance for an agricultural aircraft operator. Prior to departure, the pilot had indicated that he planned to follow highway 12 through Lolo Pass, to Lewiston, Idaho, to Walla Walla, Washington, and finally into Hermiston. Witnesses also said that they thought that the pilot may have been planning to stop at Lewiston and/or Walla Walla.

After departure, the pilot did not contact any FAA air traffic facilities, and during a later review of recorded radar data the aircraft could not be positively identified. The aircraft was next seen about one hour after departure flying through mountainous/hilly terrain about 75 miles west of Missuola. At that time, the aircraft was passing through Lookout Pass at about 200 feet above ground level (AGL). Two Idaho Department of Transportation workers, who were near the summit of the 4,738 foot pass, noticed the aircraft and reported that "...the plane was obviously trying to follow the freeway." They said that the aircraft, which was on a northerly heading at the time it was observed, "...was headed into Idaho, west-bound along Highway I-90." According to the workers, the aircraft was only visible for a few seconds, and then it quickly disappeared into the low clouds, drizzle, and snow. They said that the aircraft had been flying just below the low clouds, and was hard to see because "...it was raining and snowing pretty hard." The wreckage was located two days later about three miles north of where it had last been observed.

METEOROLOGICAL INFORMATION

The Surface Aviation Weather Report (SA) for Missoula, Montana, about 75 nautical miles east of the accident site, taken at 1850 Universal Time Coordinate (UTC), about 10 minutes before the accident, reported 5,500 scattered, 8,500 scattered, estimated 30,000 broken, 20 miles visibility, temperature 58 degrees, dewpoint 42 degrees, winds 340 at 7 knots, altimeter 29.85 inches, with rain showers of unknown intensity to the southwest.

The Special SA (SP) for the same location, taken at 1906 UTC, about five minutes after the accident, reported 5,500 scattered, 8,500 scattered, estimated 30,000 broken, visibility 30 miles with a thunderstorm in the vicinity of the reporting station, winds 280 at 15 knots, altimeter 29.86 inches, with cumulonimbus and rain showers of unknown intensity southwest moving northeast.

The Automated Weather Observation System (AWOS) generated SA for Coeur d' Alene, Idaho, about 50 nautical miles west of the accident site, taken at 1856 UTC, reported measured 2,400 broken, 3,300 overcast, ten miles visibility, temperature 47 degree, dewpoint 36 degrees, winds 180 degrees at eight knots, and an altimeter setting of 29.99 inches.

The AWOS SA for the same location taken at 1916 UTC showed 2,700 scattered, measured 3,400 broken, 4,400 broken, visibility 10 miles, temperature 48 degrees, dew point 36 degrees, winds 180 degrees at nine knots, and an altimeter setting of 29.98 inches.

The Missoula Terminal Forecast (FT), Amendment One, valid at 1915 UTC was for 5,000 scattered, ceiling 8,000 broken, winds 280 degrees at 12 knots gusting to 18 knots, with occasional thunderstorms and light rain showers, and associated wind gusts to 30 knots.

AIRMET (WA) Sierra, issued at 1945, for IFR and mountain obscuration in Idaho, Montana, and Wyoming, warned of occasional mountain obscuration due to clouds and precipitation, and showed these conditions to continue until 0800 UTC.

AIRMET Zulu for Washington, Montana, and Idaho, which was also issued at 1945 UTC, warned of occasional moderate mixed and rime ice in clouds and precipitation above 8,000 feet.

Witnesses who were in the area of Lookout Pass around the time of the accident reported that it was snowing hard, and that there were low-hanging clouds, fog, and rain. Witnesses also said that the clouds were "...thicker and much closer to the ground..." on the northwest side of the pass.

IMPACT AND WRECKAGE INFORMATION

The impact site was located at the 5,650 level of a 6,400 foot ridge, which was located on a 340 degree magnetic heading from Lookout Pass. The aircraft had impacted the southeast side of two trees that were estimated to be about 60 feet in height. Impact scarring was present at about 45 feet above the ground, and the right elevator was hanging in one of the trees at about the 40 foot level. A number of branches had been broken off below the impact marks, and there were numerous vertical scratches on the trunk of the trees between these marks and the ground.

The aircraft came to rest with its nose pointing uphill about 20 degrees to the right of the fall line of a 36 degree slope. The engine compartment, cabin, and fuselage forward of the empennage were all extensively damaged and/or consumed by an intense fire. The left wing, which was located about 10 feet northwest of the burned fuselage, was partially destroyed by fire, ripped and torn open, and showed considerable crushing and denting from the impact. The outboard portion of the left aileron had separated from the rear wing spar, and it was located about eight feet northwest of the left wing. The left lift strut was still attached to the wing, but had torn apart about six inches from where it attaches to the fuselage. The right wing, which was still attached to the fuselage by its lift strut, was found inverted on the southeast side of the fuselage. This wing, which had been destroyed by fire from its root to a point about one-half the span of the flap, showed direct rearward crushing along the entire remaining span. The empennage, which was laying adjacent to the burned fuselage, showed tearing and pulled rivets where it had separated from the forward part of the fuselage. The right horizontal stabilizer and right elevator had separated from the empennage, but all other flight surfaces were present. The propeller was still attached to the crankshaft, with one blade showing a substantial number of chord-wise scars and leading edge indentations. The other blade showed chord-wise scarring on the inner portion of its span, and was melted and distorted by fire on its outboard portion. The propeller spinner was crushed against the hub and showed rotational scarring and twisting opposite the direction of normal engine rotation. The engine had sustained substantial impact and thermal damage to the area around the cylinders, and the magnetos had melted from the mounting area on the accessory case. The cabin doors had separated from the fuselage and were found laying near the primary wreckage. The flaps were both in the up position, and the horizontal stabilizer was found in the full nose down trim position. Control continuity was confirmed to the right aileron and to all empennage flight control surfaces.

ADDITIONAL INFORMATION

According to the Wallace County Coroner (208-786-5121), an autopsy was not performed due to the extensive amount of thermal damage.

The aircraft was released on 9/24/93 at the scene of the accident. It was released to Specialty Aircraft of Redmond, Oregon, a representative of the owner.

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