NTSB Factual Report

HISTORY OF FLIGHT

On October 16, 1991, about 1030 mountain daylight time, N19AR, a Maule M-5-235C airplane, registered to Western Air Research, Inc., impacted mountainous terrain while maneuvering and was destroyed near Moran, Wyoming. There was a ground fire. The commercial pilot and his two passengers were fatally injured. Variable meteorological conditions prevailed and a visual flight rules (VFR) flight plan had been filed. The aerial observation flight was conducted under 14 CFR 91 and was engaged in a non-exclusive contract with the Wyoming Fish and Game Department. The local flight had departed from Jackson, Wyoming, about 0830. The intent of the flight was aerial observation, specifically wildlife tracking activities.

According to FAA records, the pilot received three weather briefings via the Direct User Access Terminal (DUAT) in preparation for the flight. The briefings were received at 2103 one day prior to the accident, and again at 0603 and 0648 on the day of the accident. The pilot then filed a VFR flight plan via DUAT at 0651 for a flight from Driggs, Idaho, to Jackson, and then on to a wildlife survey 25 nautical miles northeast of Driggs. The pilot reported his estimated time of departure to be 0735, the duration of the flight to be four hours, and the total fuel on board to be five hours.

According to the operator, the pilot departed by himself from Driggs after the airplane had been loaded with five hours of fuel. The pilot flew to the Jackson Hole Airport and landed about 0810. Two employees of the Wyoming Fish and Game Department boarded the airplane, and the flight departed from the Jackson Hole Airport about 0830 on a routine grizzly bear biotelemetry radio tracking and observation mission. According to the operator, bear tracking frequently involves maneuvering the airplane at reduced airspeeds and below 500 feet above mountainous terrain.

The airplane was expected to return to the Jackson Hole Airport about 1140, but it never arrived. No distress calls were reported from the airplane. Radar data believed to be associated with the aircraft indicated an altitude of approximately 11,400 feet above mean sea level (msl) and a northbound flight path from Jackson about 0840 on the morning of the disappearance.

After several extensive searches, the wreckage was not located and was listed as missing. On September 25, 1995, a hiker discovered the wreckage in heavily wooded, mountainous terrain.

The accident occurred during the hours of daylight at a location of 43 degrees, 55.8 minutes North and 110 degrees, 05.4 minutes West.

PERSONNEL INFORMATION

The pilot, age 47, was a certificated commercial pilot with ratings for single-engine land and sea airplanes, instrument airplanes, and helicopters. He also possessed a certified flight instructor certificate with a rating in single-engine airplanes. According to FAA records, the pilot's most recent second class medical certificate, dated April 22, 1991, contained no waivers or limitations. His most recent FAA Part 135 check ride was successfully completed in a Maule M-5-235C on July 29, 1991. The pilot reported over 5,200 hours of total flight time as of December 21, 1990, of which over 3,200 hours were recorded as "mountain and low-flying" hours.

AIRCRAFT INFORMATION

According to the operator, the accident airplane was outfitted with telemetry equipment and computer recording devices for the purposes of bear tracking. The four-place, single-engine airplane could carry up to five hours of fuel. An examination of the airplane's engine and airframe logbooks did not reveal any unresolved discrepancies prior to departure the day of the accident.

METEOROLOGICAL INFORMATION

The Safety Board obtained a compilation of meteorological data (excerpts attached) from the National Weather Service for western Wyoming and the Jackson area about the time of the accident.

Strong southwesterly surface winds with gusts ranging up to 22 knots were reported at the Jackson Hole Airport about the time of the accident. The airport is located about 33 nautical miles southwest of the accident site at an elevation of 6,445 feet msl. Similar southwesterly wind conditions with gusts ranging up to 17 knots were reported at the Yellowstone Regional Airport in Cody, Wyoming, about the time of the accident. The airport is located about 70 nautical miles northeast of the accident site.

A meteorological impact statement was issued for the time of the accident and reported the following:

Moderate local severe turbulence below 18,000 feet with local strong updrafts and downdrafts over and along the eastern slope of the Rocky Mountains in Montana and Wyoming. Strong southwesterly winds developing over the western half of Montana and western Wyoming with gusts to 60 knots possible.

WRECKAGE AND IMPACT INFORMATION

The airplane wreckage was examined at the accident site on September 26, 1996. The airplane came to rest in heavily wooded, mountainous terrain at an elevation of about 9,200 feet msl. The wreckage was distributed along a path parallel to a ridge line located about 1/2-mile south of a 10,870-foot tall mountain peak.

The wreckage distribution path was measured to be about 200 feet in length and oriented along a magnetic bearing of 080 degrees. The angle of impact was estimated to be about 35 degrees. A tree measuring 18 inches in diameter marked the beginning of the path. This tree had been sheared off about 75 feet from its base and pieces of aluminum aircraft skin were found in its vicinity. About 75 feet downrange from this tree, another sheered tree was found. The tree was sheared off about 35 feet from its base and pieces of the tailwheel strut and right wing tip were found in its vicinity.

About 150 feet down range from the initial sheared tree, the propeller was found. A tree trunk located in the vicinity of the propeller exhibited evidence of circumferential gouging. The fuselage, cabin area, tailcone, wings, and engine remained attached to each other and were found about 25 feet from the propeller. Evidence of a ground fire surrounded this wreckage and extended to the east of the wreckage about 50 feet.

All primary and secondary flight control surfaces were accounted for at the accident site. Control cable continuity to all flight control surfaces was verified. No evidence was found to indicate a flight control malfunction or in-flight structural failure.

The instrument panel was destroyed by fire. No indications from the cockpit could be read.

The engine, a Lycoming model O-540-J1A5D was examined. The engine was found in a nose-down attitude. No holes were found in the crankcase. Evidence of corrosion and thermal damage was found on the exterior of the engine. No evidence of internal metal contamination or component failure was found. The oil sump/induction plenum, carburetor, and accessories were melted. An examination of three of the fine-wire sparkplugs revealed undamaged and clean electrodes. The examination of the engine did not reveal any evidence of preimpact mechanical malfunction.

The two-bladed, fixed-pitch Hartzell metal propeller was examined. The propeller was separated from the engine at its flange and was found lying about 50 feet from the engine. One blade exhibited evidence of slight "S" bending, with the center of the "S" located about mid-span along the blade. The other blade exhibited "S" bending along the last six inches of its tip. The aluminum propeller spinner remained attached to the propeller hub. The spinner exhibited evidence of circumferential wrinkling and torsional damage.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy and toxicological analysis were not performed due to a lack of suitable specimens.

ADDITIONAL INFORMATION

The aircraft wreckage was released to Mr. Fred C. Reed, President, Western Air Research, Inc., on September 26, 1995.

NTSB Probable Cause

The pilot's failure to maintain clearance and altitude from terrain while maneuvering, and his failure to adequately compensate for the wind conditions. Factors contributing to the accident are terrain-induced turbulence, unfavorable winds, gusty high winds, and low altitude flight.