SEA08LA105

The non instrument-rated private pilot departed under visual flight rules (VFR) for a planned cross country flight over mountainous terrain. During the cruise phase of the flight, the pilot was receiving radar flight following service. As the flight progressed, due to clouds, the pilot requested a lower altitude from the air traffic controller who was working the flight. Radar data showed that the airplane descended from the original cruise altitude, then performed a series of turns while continuing to descend prior to radar contact being lost. A witness located adjacent to the accident site reported hearing an airplane fly overhead at a low altitude followed by the sounds of the airplane impacting the ground. The witness added that at the time he heard the airplane fly over, visibility was around 100 to 150 feet with near "whiteout" conditions due to heavy snow falling. Examination of the airframe and engine revealed no mechanical anomalies.

History of flight

On April 7, 2008, about 1530 mountain daylight time, an amateur built Glasair III airplane, C-GGTM, was substantially damaged when it impacted terrain near Cheyenne, Wyoming, while maneuvering. The private pilot, sole occupant of the airplane, was killed. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the nearest official weather reporting station and instrument meteorological conditions prevailed in the accident area. The personal cross-country flight originated from the South Big Horn County Airport (GEY), Greybull, Wyoming, about 1415 with an intended destination of Larned-Pawnee County Airport (LQR), near Larned, Kansas. No flight plan was filed.

A witness located adjacent to the accident site reported hearing an airplane fly overhead at a low altitude followed by a muffled "thud" shortly thereafter. The witness located the wreckage a few minutes later and called 911. The witness added that at the time he heard the airplane fly over, visibility was around 100 to 150 feet with near "whiteout" conditions due to heavy falling snow.

Radar data provided by the Denver Air Route Traffic Control Center (ARTCC) indicated that radar contact with the accident airplane was initially obtained about 21 miles northeast of Worland, Wyoming at an altitude of 14,900 feet mean sea level at 1429:10. Radar data depicted the airplanes flight path was oriented on a southeasterly course at an altitude of 15,500 feet msl until 1515:13, where the airplane started to descend while remaining on a southeasterly heading.

At 1518:24, the radar ground track showed that the pilot made a left 90-degree turn while continuing the descent. At 1519:31, the airplane was observed making a left 270-degree turn to a southerly heading while descending to an altitude of 7,400 feet msl. At 1522:23, the ground track showed the airplane making a left turn to a northern heading followed by a right turn to an easterly heading. At 1525:35, the ground track showed the airplane making a right turn to a southerly heading at an altitude of 5,800 feet msl. The last radar return was at 1526:42, about 7 miles north of the accident site at an altitude of 5,800 feet msl.

Personnel information

The pilot held a Canadian private pilot certificate with airplane single-engine land and multi-engine land ratings. A third-class airman medical certificate was issued on September 11, 2006, with no limitations stated. The pilot's logbook was not recovered for examination. Review of the Aircraft Journey Log revealed that the pilot had accumulated 246.6 hours in the accident airplane as of March 30, 2008.

Aircraft information

The amateur built experimental two-seat, low-wing, retraceable-gear airplane, serial number (S/N) 3262, was built in 2003 by the registered owners. It was powered by a Lycoming IO-540-K1A5, rated at 340 horse power engine and equipped with a Hartzell constant speed propeller. Review of the Aircraft Journey Log revealed that an annual inspection was completed on March 24, 2008, at a total airframe time of 309 hours.

Meteorological information

A review of recorded data from the Cheyenne Regional Airport's (CYS) automated surface observation station, located 27 miles south of the accident site, at an of elevation 6,159 feet, reported at 1453; wind from 190 degrees at 11 knots, visibility 10 statute miles, cloud condition overcast at 600 feet above ground level (agl), temperature -1 degree Celsius, dew point -3 degrees Celsius, and an altimeter setting of 29.81 inches of Mercury.

At 1553, CYS reported wind from 200 degrees at 8 knots, visibility 10 statute miles, cloud conditions overcast at 1,200 feet agl, temperature -1 degrees Celsius, dew point -4 degrees Celsius, and an altimeter setting of 29.82 inches of Mercury.

At 1625, CYS reported wind from 210 degrees at 14 knots, visibility 1.5 statute miles, light snow, cloud conditions overcast at 1,200 feet agl, temperature -1 degrees Celsius, dew point -3 degrees Celsius, an altimeter setting of 29.84 inches of Mercury, and snow began at 1619.

Communications

Review of radio communication transcripts provided from Denver ARTCC revealed that the pilot initially contacted ARTCC at 1433:33.

At 1513:55, the pilot radioed Denver Center stating "...denver center charlie golf golf tango mike uh like to descend here for the cloud." The controller approved the descent per the pilots request.

At 1514:28, the pilot stated, "...yeah golf golf tango mike, I'd like to descend uh for the cloud maybe 9,500." The controller informed the pilot to maintain VFR and advised the pilot that the minimum IFR altitude in the area was 10,000 feet. The pilot acknowledged the controller at 1514:54.

At 1519:42, the controller stated, "...golf tango mike just for verification do you have terrain in sight minimum IFR altitude is one zero thousand." The pilot replied at 1519:48, "yeah we're okay here we've got some clouds uh gonna have to deviate."

At 1521:24, the controller stated, "charlie golf golf tango mike in the vicinity of Laramie light rime ice was reported out of one one thousand one hundred and lower."

No further radio communication was received from the accident airplane despite multiple attempts by the controller.

Wreckage and impact information

Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that the airplane impacted an open field and came to rest in an upright position at a field elevation of 5,935 feet msl. From the initial ground impact scar to the main wreckage was about 170 feet in length and on a heading of about 15 degrees true. Examination of the airplane revealed that all of the primary flight controls were located at the accident site.

Examination of the recovered airframe and flight control system components revealed no evidence of preimpact mechanical malfunction.

Examination of the engine revealed it remained attached to the firewall. Rotational continuity was established throughout the engine and valve train when the crankshaft was rotated by hand using the propeller. The propeller remained attached to the crankshaft. One blade exhibited leading edge polishing and 45 and 90 degree chordwise scratching. The blade was bent aft about 90 degrees and exhibited "S" bending near the blade tip. The other propeller blade exhibited "S" bending and 45 degree chordwise scratching. Examination of the recovered engine and system components revealed no evidence of preimpact mechanical malfunction.

Medical and pathological information

The Laramie County Coroner conducted an autopsy on the pilot on April 8, 2008. The forensic pathologist determined that the cause of death was "Multiple Blunt Force Injuries."

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had negative results.