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On October 18, 1998, approximately 1850 mountain daylight time, a Piper PA-28-235, N8537N, was destroyed following impact with terrain while in cruise flight near Buffalo, Wyoming. The non-instrument rated private pilot and his passenger were fatally injured. The airplane was owned/operated by the Cherokee Aero Club of Pierre, South Dakota, under Title 14 CFR Part 91. Instrument meteorological conditions prevailed for the night cross-country personal flight which originated from Mobridge, South Dakota, approximately 2 hours 35 minutes before the accident. A VFR flight plan had been filed with Billings, Montana, as the destination. All times are in mountain daylight time, unless otherwise noted.
According to FAA documents, the pilot telephoned Huron Automated Flight Service Station (AFSS), at approximately 1300, for a weather briefing in preparation for his flight from Pierre to Mobridge, and then on to Billings, Montana. The FAA documents indicate that the pilot was given a full briefing which included all NOTAMs for his route of flight. The pilot did ask the briefer if there was any flight activity in the northern half of the Powder River Military Operations Area (MOA), which he was planning to fly through, and was told that "there was nothing at this time."
FAA records further indicate that the pilot called Huron AFSS again at 1512 and filed a VFR flight plan from Mobridge, South Dakota, direct to Billings, Montana. The flight plan indicated that he would be flying at an altitude of 6,500 feet, at 135 knots, and his planned time en route was 3.5 hours (see attachment). The records indicate that the AFSS briefer advised the pilot of light to occasionally moderate turbulence below 14,000 feet, in the northeast corner of Wyoming. The pilot departed Mobridge at 1530, but shortly after getting airborne, returned to Mobridge. The pilot reported to the lineman that the airplane's door had "popped" open, and that he could not receive radio transmissions.
The pilot refiled his flight plan with the AFSS, and had the airplane's fuel tanks topped off with 6.7 gallons of fuel. The lineman who refueled the airplane reported that the pilot was "a little nervous and uneasy." The pilot departed a second time at 1615, and reported to the AFSS briefer that "his radios were working fine, he just needed to turn the volume up."
Radar data indicated that that pilot flew a magnetic course of approximately 260 degrees (263 degrees was needed to fly directly to Billings) until he approached Glad Valley, South Dakota. Then he turned south until he joined the Dupree VOR 211 degree radial for approximately 20 nautical miles (nm) and then turned west. The last recorded radar return (at 1710) was located approximately halfway between Opal and Marcus, in South Dakota.
The pilot contacted Denver Flight Watch at 1743, and reported that he was over Faith, South Dakota (radar data indicated that he passed Faith 49 minutes earlier, at 1654). He stated that "it was getting a little soupy out here," and he requested a weather update. The weather update was transmitted, but the pilot never responded that he received it.
FAA records indicate that the pilot radioed Denver Flight Watch at 1845 and asked if they could "help us, ah, locate where we're actually at." The pilot further stated that he was too far away from a VHF Omnidirectional Range (VOR) to "plug into, and, ah, right now we're showing 133 miles...ah, east of and probably south of Billings, but we're not exactly sure...could you, ah, kind of pinpoint us, for us, if you could." The pilot then reported that he was on a heading of 300 degrees and crossing a north-south interstate.
Denver Flight Watch attempted to assist the pilot, but approximately 2 minutes later, communication attempts became unsuccessful. The airplane was found the next day at approximately 7,000 feet msl in the Bighorn Mountains. The accident site was located approximately 100 nm south of the pilot's VFR filed route.
According to FAA records and the pilot's flight logbook, the pilot received his private pilot certificate on April 2, 1978. The pilot's flight logbook documented that he had completed his required FAA Part 61 flight review on September 22, 1997. His flight logbook indicated that he had accumulated 791 hours of flight experience by the time of the accident; 13 hours of which were accumulated in 1998, and 7 hours of flight experience in 1997.
The pilot was not instrument rated. According to the pilot's flight logbook, he had 359 hours of night flying. A witness reported that "the pilot liked to fly at night and did so quiet frequently." Another witness reported that the pilot had been given training in the airplane's global positioning system (GPS) navigational receiver, but the pilot had recently reported that he "had difficulty setting the GPS."
The airplane was a propeller-driven, four seat airplane, which was manufactured by Piper Aircraft Corporation in 1969. It was powered by a Textron Lycoming O-540, six cylinder, reciprocating, horizontally opposed, carbureted engine which had a maximum takeoff rating of 235 horsepower. At the last annual inspection on September 4, 1998, the tachometer reading was 1560, and the airframe had accumulated 3,212 hours.
According to a witness, the airplane, which was purchased in the spring of 1997, was "fully IFR equipped, and had a non-IFR certified Garmin GPS navigational receiver in it."
At 1853, the weather conditions at the Johnson County Airport (elevation 4,968 feet), Buffalo, Wyoming, 360 degrees 15 nm from the accident site, were as follows: wind 350 at 10 knots; cloud condition 1,000 feet overcast; temperature 37 degrees Fahrenheit; dew point 36 degrees Fahrenheit; altimeter 30.28 inches of mercury (see attached meteorology group chairman's report). The sunset at Johnson County Airport was at 1818; the end of civil twilight was 1847; and the moonset was 1755.
The NTSB's meteorology group chairman stated that weather conditions in the Spearfish, South Dakota, area had deteriorated, during the time period of 1700, with "gradually lowering ceilings" (see attached report). Weather conditions for Gillette, Wyoming, at 1755, were reported to be light rain with a ceiling of 2,100 feet agl. By 1836, the cloud ceilings had lowered to 1,500 feet agl with scattered clouds as low as 800 feet. According to the meteorology group chairman, "these weather conditions continued west from Gillette to the accident site." He did say that 10 to 15 nm south of this line "weather conditions improved to visual meteorological conditions."
AIDS TO NAVIGATION
The Crazy Woman VOR, located approximately 26 nm south of Buffalo, Wyoming, went off the air on October 17, 1998, at 1950. The FAA reported that heavy snow fall in the area of the VOR "downed power lines and cut the power to the VOR." They further reported that the VOR was back to normal operation on October 19, 1998, at 2000.
The pilot was not given this information during his preflight briefing by the AFSS briefer.
WRECKAGE AND IMPACT INFORMATION
The airplane's impact site (elevation 7,000 feet) was in the Bighorn Mountain Range, approximately 15 nm south of Buffalo (N44 degrees 07.9 minutes, W106 degrees 49.4 minutes), or approximately 280 degrees for 18 nm from the Crazy Woman VOR. The airplane impacted heavily wooded (up to 12 inch in diameter trees) rising, mountain terrain, with an up-slope of approximately 30 to 35 degrees. The forest floor was littered with tree limbs with signatures (diagonal cuts with paint transfer) which suggested propeller slashes. The longitudinal path of remaining vertical tree trunks was oriented 290 degree, with shorter tree trunks on the north side of the path suggesting that the airplane entered the forest in level flight with an approximate 25 degree right bank (see photographs).
The airplane was found on its left side with both wings separated from the fuselage, and both wings were fragmented. Pieces of wing were identified which displayed leading edge compression damage which extended aft to the main spar (see photographs). The horizontal stabilator was found separated from the empennage. All control surfaces were accounted for; control cable continuity was not possible due to impact damage. The airplane's instrument panel was destroyed with the following exceptions: the directional indicator's heading bug was on 312 degrees; the turn coordinator was in a right turn; the throttle was 1 inch aft; the mixture was 1 inch aft; and the propeller was 1 inch aft. The fuel selector was found on the right main tank. The emergency locator transmitter did function and assisted in locating the wreckage.
On November 17, 1998, the engine was examined in Greeley, Colorado. The engine's crankshaft rotated by hand to confirm engine continuity, and cylinder "thumb" compression checks on all 6 cylinders did not identify any anomalies. Valve continuity was visually confirmed on 5 cylinders; the #1 cylinder was severely impact damaged and the pushrods were missing. Both magnetos were removed and bench tested. Spark was observed on all leads of both magnetos during testing. The engine carburetor's metal floats exhibited hydraulic deformation.
The two-bladed metal propeller remained attached to the crankshaft flange. One propeller blade was bent approximately 90 degrees aft starting about 12 inches out from the hub, and then was twisted. Leading edge gouges and blade polishing was noted. The second blade was curled aft and then bent sharp about 8 inches from the tip. The blade tip area exhibited gouges and twisting. Chordwise striations and diagonal scratches were found on both propeller blade cambered surfaces.
All major components of the airplane were accounted for at the accident scene. There was no evidence of pre or postimpact fire. No preimpact engine or airframe anomalies, which might have affected the airplane's performance, were identified.
MEDICAL AND PATHOLOGICAL INFORMATION
An autopsy on the pilot was performed by Dr. William E. Doughty, a forensic pathologist, with Sheridan Pathology Associates, P.C., Sheridan, Wyoming, on October 20, 1998.
Toxicology tests were performed on the pilot by FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. According to CAMI's report (#9800295001), the pilot's carbon monoxide and cyanide tests were not performed due to lack of suitable specimens, and no ethanol was detected in the urine. The drug Pseudoephedrine, an over-the-counter decongestant with a trade name Sudafed, and its metabolite Ephedrine, were detected in the urine. No blood was available for analysis.
The airplane, including all components and logbooks, was released to a representative of the owner's insurance company on July 6, 1999.