NTSB Factual Report

HISTORY OF FLIGHT

On September 9, 1997, at about 1115 mountain daylight time, a Piper PA-12, N3637M, registered to the pilot, and operated as a 14 CFR Part 91 personal flight, collided with power lines while maneuvering through a valley near Horseshoe Bend, Idaho. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The airplane was destroyed by a post crash fire and the airline transport pilot, the sole occupant, was fatally injured. The flight had originated from a private airstrip in a wilderness area located about 30 miles east of Cascade, Idaho, about one hour prior to the accident.

Another pilot who was flying in a similar make and model aircraft behind the accident airplane witnessed the accident. The witness reported that they had originally taken off from Caldwell, Idaho, at about 0730 that morning to fly the approximate one-hour flight to a private airstrip called Sulphur Creek, for breakfast. The witness reported that the flight was uneventful. The witness reported that after breakfast, the two took off with the accident aircraft in the lead, and flew southbound along the Sawtooth Mountains for about 45 miles, then turned west bound towards Idaho City and Horseshoe Bend.

The witness reported that the accident airplane entered the canyon (traveling east to west) below the ridge line. The witness stated that he was higher and about one-eighth of a mile behind the lead airplane. The witness estimated that their airspeed was approximately 80 to 90 miles-per-hour and centered in the canyon. The witness reported that there was a turn (to the left) in the canyon just prior to a straight stretch. As the witness was coming around the turn, the lead pilot transmitted that there was a car on the road. The witness stated that he looked down to find the car and the lead airplane, then glanced back at his cockpit instruments before looking back at the lead airplane. The witness stated that when he looked back at the lead airplane he saw that it was upside down and traveling backwards. The witness stated that he did not know what had happened at first, then he saw the power lines and the power poles on either side of the canyon. The lead aircraft then hit the ground. The witness stated that he pulled up to circle the wreckage and observed a small fire at the accident site. The witness then called for help and returned to Caldwell.

OTHER DAMAGE

The post crash fire ignited the dry grass and low shrub brush. Approximately 150 acres were burned before fire crews were able to bring the fire under control.

One wooden power pole located on the north side of the canyon was broken in two. Three one-quarter inch wires, which were strung across the canyon, were broken. Two of the wires carried 25,000 volts, and the third wire was neutral. The Idaho Power Company reported that the minimum distance above the ground for these wires was 33 feet, and the maximum height above the ground was 60 feet. The wires were unmarked.

As soon as the fire was brought under control, power company personnel replaced the wooded pole and restrung the wires.

PERSONNEL INFORMATION

At the time of the accident, the pilot held an Airline Transport pilot certificate. The pilot also held a flight instructors certificate and was rated in single-engine land and multi-engine land aircraft. The pilot's flight logbook was not made available for review, however, the pilot listed a total flight time of 7,500 hours at the time of his last medical examination on May 22, 1997.

The pilot held a class II medical certificate with a restriction that he must wear corrective lenses.

The pilot who was flying in the other accident reported that the accident pilot appeared well rested and in good health.

WRECKAGE AND IMPACT INFORMATION

The wreckage was positioned inverted on level ground approximately 200 yards west of the impact area with the transmission wires. Broken plexiglass was found on the dirt road directly under and to the west of where the transmission wires were strung across the canyon. The plexiglass pieces displayed scratches along the surface.

The wreckage was pointing on a heading of 120 degrees. Directly ahead of the wreckage, evidence of ground impact was noted. At the beginning of the ground signature, wooden pieces of the left wing tip were found. Approximately 17 feet further, a larger ground signature measuring approximately 15 feet was noted. Among this disturbance, pieces of plexiglass and yellow paint chip and fabric remnants were noted. Approximately 25 feet further, the wreckage came to rest inverted. The fuselage and the inboard sections of the wings had been consumed by the post-crash fire. The fabric was completely burned away, however, the structure remained intact with severe heat distress. A section of transmission wire remained wrapped around the fuselage and engine. The cockpit was destroyed by the fire.

The right wing remained attached to the fuselage. The inboard section of the wing and the fuel tank were burned. The strut remained attached to both the wing and the fuselage. Both the aileron and the flap remained attached to their respective hinges.

Both the horizontal and vertical stabilizers remained attached, with the elevators and rudder attached to their respective hinges. The vertical stabilizer was bent slightly to the right near the tip. The left side horizontal stabilizer was bent forward.

The left wing remained partially attached to the fuselage and was twisted aft. The strut remained attached at the wing and was bent. The other end of the strut broke away from the fuselage. The aileron remained attached at the hinges. The flap was burned away, however, the hinges remained in place. Transmission wire was wrapped around the wing.

Control continuity was established from the wings to the cockpit area, and from the empennage to the cockpit area.

The engine displayed evidence of severe heat distress. The accessory section was destroyed by the fire. Cylinders one and three remained intact. Cylinders two and four displayed heat distress with melting of the cylinder head and evidence of ground impact. The propeller broke away at the flange. Evidence of scratch marks were noted on the propeller spinner.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy was performed by Frank A. Roberts, M.D. from the Boise County Coroner's Office. The autopsy report indicates that the cause of death was due to severe total body burns as a result of the aircraft accident. The report also indicates evidence of severe two-vessel coronary atherosclerosis involving the anterior descending and right coronary vessels.

Tissue samples were taken and sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma City, Oklahoma, for analysis. The results of the analysis were negative.

ADDITIONAL DATA/INFORMATION

The wreckage was removed by personnel from SP Aviation and taken to Boise, Idaho.

The wreckage was released to the pilot's representative on September 19, 1997.

NTSB Probable Cause

the pilot's failure to maintain clearance from transmission wires. The wires were a factor.