History of Flight
On July 1, 2019, about 1359 mountain daylight time, a Schempp Hirth Arcus M glider, registration N215MM, was destroyed when it collided with terrain near Ephraim, Utah. The pilot and pilot-rated passenger sustained fatal injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight while participating in a soaring competition.
Data from the glider’s PowerFLARM-IGS flight recorder indicated that the glider departed Nephi Municipal Airport (U14), Nephi, Utah, at 1230:47. At 1238:19, the glider encountered its first thermal and gained an additional 2,158 ft in altitude. Over the next 40 minutes, the glider flew north, then east, encountering four more thermals, with the pilot climbing to 6,935 ft above ground level (agl). At 1323:30, the glider turned south over Manti-La Sal National Forest (Wasatch Plateau). During the next 36 minutes, the glider continued roughly south-southwest along a ridgeline, circling in several areas, but continued to descend. The last recorded data point, at 1359:47, indicated the glider was in a right turn at about 185 ft agl.
Meteorological Information
The National Weather Service Surface Analysis Chart for the accident time depicted a dissipating stationary front extending west to east over southern Idaho and Wyoming. A high-pressure system at 1014 hPa was located over southern Utah immediately south of the accident site, with a general high-pressure ridge extending over the state. Station models around the accident site reported clear skies, light wind of 5 knots, and temperatures in the upper 80s to low 90s °F.
A High-Resolution Rapid Refresh (HRRR) numerical model for an elevation of 7,431 ft indicated a surface temperature of 25.5°C (78°F), a dew point of -3.0°C (27°F), relative humidity of 15%, and density altitude about 10,016 ft. The sounding supported strong thermal activity from the surface through 17,500 ft. The lifted condensation level was at 11,425 ft agl (18,856 ft msl), with the convective condensation level above at 12,961 ft agl. Precipitable water was 0.31 inches. The sounding was too dry for cloud formation, and none were indicated. The lifted index indicated a conditionally unstable atmosphere.
The wind profile showed surface wind from the southwest at 9 knots, backing to south-southwest through 15,000 ft, then veering to the southwest with height. The mean 0 to 6 km (18,000 ft) wind was from 230° at 15 knots, with maximum wind at 40,000 ft from 220° at 53 knots. GOES-17 visible satellite imagery for 1546 showed clear skies over the accident site with fair weather cumulus clouds on the eastern slopes of the mountain range immediately east of the site.
Wreckage and Impact Information
The wreckage was located in mountainous terrain about 4.25 miles northeast of Ephraim, Utah, at an elevation of 7,628 ft mean sea level, within a 50-ft area. The main wreckage included the left wing, cockpit, fuselage, empennage, and engine. The forward fuselage and cockpit area were extensively crushed and deformed.
The right wing had separated from the glider upon impact with a tree and was located about 20 ft east of the main wreckage. The inboard section and most of the outboard portion of the right wing were wrapped around the tree; the remaining outboard portion remained with the main wreckage. The right inboard section remained attached to the outboard section, but the wingtip had separated. The left inboard wing remained attached to the fuselage. Fractures and deformations along the wingspan were consistent with impact forces. The outboard left wing was fractured and bent backward. All ailerons remained attached to their respective wings.
The steel fuselage truss was deformed and fractured in multiple places. The fuselage shell fractured about halfway along its span; all flight control cables remained attached to their attach points. The empennage was fractured from the fuselage just forward of the vertical stabilizer but remained attached by control rods and cables. The vertical stabilizer was rotated 180°, with its leading edge on the ground. The horizontal stabilizer remained attached to the top of the vertical stabilizer and engaged with mount points. Elevator hinges were intact and undamaged; the rudder remained intact. Aileron controls were fractured and deformed between the forward control stick and tunnels, consistent with extensive forward fuselage damage. All fractures in flight controls had a dull, grainy appearance; deformation was consistent with overstress separation.
Additional Information
The FAA Glider Flying Handbook (FAA-H-8083-13A) states that it is not uncommon for thermals to exist with slope lift. When a thermal is encountered along a ridge, a series of S-turns can be made into the wind, with drift back to the thermal after each turn if needed, and never continue the turn to the point that the glider is turning toward the ridge.
Medical and Pathological Information
The Utah Department of Health, Office of the Medical Examiner, performed an autopsy on the pilot and passenger. The cause of death for both was multiple blunt force injuries. The FAA Forensic Sciences Laboratory conducted toxicology tests on specimens from the pilot, detecting the previously reported medications rosuvastatin, tadalafil, and lansoprazole.