History of Flight
On July 13, 2017, at approximately 0940 mountain daylight time, an Aviat A1-B airplane, registration N211AM, impacted terrain while maneuvering near Herriman, Utah. The flight instructor and the pilot receiving instruction were fatally injured, and the airplane was destroyed by a post-impact fire. The airplane was privately owned and operated by the instructor under Title 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight, which had departed South Valley Regional Airport (U42) in West Jordan, Utah, at about 0927.
A law enforcement officer driving west at a higher elevation observed the airplane flying low up a canyon. After briefly turning away, he saw the airplane execute a steep right turn, its nose dropped, and it appeared to lose altitude rapidly. The officer noted that the airplane seemed to have limited escape options and was making a last-ditch attempt. He could see the tops of both wings during the turn but saw no smoke. Continuing west, he lost sight of the airplane and later pulled over, eventually driving further up the canyon where he saw smoke rising from the area where the airplane had last been seen.
Radar data from the Federal Aviation Administration showed that after takeoff, the airplane flew on a southwesterly heading into the box canyon. During the final 1.5 minutes of flight, the airplane reached an altitude of 6,000 ft.
Personnel Information
The flight instructor held an airline transport pilot certificate issued April 11, 2015, and a flight instructor certificate issued December 12, 2011. According to logbook review, he had 1,553.1 total flight hours, with 76.4 hours in the previous 90 days, including 111.6 hours in the accident airplane make and model. His most recent flight review was completed on April 9, 2013. He held a first-class medical certificate issued January 19, 2015, with no limitations.
No personal flight records were located for the pilot receiving instruction. On his most recent medical certificate application, he reported 2,887 total flight hours, with 160 hours in the previous 6 months. Review of his airman and medical certificates revealed that his medical certificate had been revoked by the Federal Aviation Administration following an investigation into his failure to report a disability, and his Australian flight certificates had previously been revoked for falsification.
Aircraft Information
The Aviat A1-B was a tandem two-seat, high-wing airplane with a steel tube frame covered with fabric and flight controls at each seat. It received its standard airworthiness certificate on October 20, 2000. The recording hour meter at the accident site was not identifiable. Examination of maintenance records showed no unresolved maintenance discrepancies before the flight.
Meteorological Information
The automated weather observation station at U42, approximately 11 miles northeast of the accident site, reported at 0935: wind from 150° at 10 knots, visibility 10 miles, temperature 81°F, dew point 59°F, and altimeter setting 30.18 inches of mercury. U42's elevation was 4,606 ft mean sea level, with a calculated density altitude of 6,980 ft. The accident site, at 7,340 ft msl, had a calculated density altitude of 10,313 ft msl based on U42 conditions.
Wreckage and Impact
The airplane came to rest on down-sloping, heavily wooded terrain about 12 miles southwest of the departure airport. Multiple broken branches were noted southwest of the main wreckage; the airplane was traveling northeast on a heading of about 060°, with the nose downslope. Trees struck were 30 ft from the main wreckage, with witness marks and broken branches about 20 ft up from the base. All major structural components were accounted for and collocated; the post-crash fire destroyed the airplane.
The wreckage rested on its right side, with airframe tubing mostly intact but fabric destroyed, exposing tubing and flight control cables. Flight control continuity was established throughout. The right wing partially separated; visual examination of the fuel cell showed no obvious holes. The left wing also partially separated, twisted and bent under the fuselage, with the fuel tank breached. The engine remained in its normal position, sustained thermal damage, but with no holes in the case. Post-crash examination revealed no evidence of a mechanical anomaly that would have precluded normal operation.
Medical and Pathological Information
The Utah Department of Health – Office of the Medical Examiner performed autopsies on both pilots. For the flight instructor, the cause of death was conflagration injury and head trauma. For the pilot receiving instruction, the cause of death was conflagration and blunt force injuries.
Toxicological testing of the flight instructor was negative for carbon monoxide, drugs of abuse, prescription drugs, and opiates. Ethanol was detected at 0.04 grams per 100 milliliters of blood, likely from postmortem production. Testing of the pilot receiving instruction was negative for carbon monoxide, volatiles, and tested-for drugs; cyanide testing was not performed.
Additional Information
The Federal Aviation Administration's pamphlet "DENSITY ALTITUDE" (FAA-P-8740-2) notes that high density altitude decreases airplane performance by reducing air density, adversely affecting aerodynamic performance and engine horsepower output, increasing takeoff distance, and reducing climb rate, especially in normally aspirated engines.
The FAA Airplane Flying Handbook (FAA-H-8083-3A) states that a given airplane consistently stalls at the same indicated airspeed at the same gross weight, configuration, and power setting if no acceleration is involved. However, steep turns, pull-ups, or abrupt flightpath changes impose maneuvering loads that result in higher stall speeds, termed accelerated maneuver stalls. These stalls tend to be more rapid and may occur at higher airspeeds or lower pitch attitudes, potentially surprising inexperienced pilots. Failure to recover promptly may lead to loss of control, including power-on spins.