HISTORY OF FLIGHTOn July 1, 2019, about 1359 mountain daylight time, a Schempp Hirth Arcus M glider, N215MM, was destroyed when it was involved in an accident near Ephraim, Utah. The pilot and pilot-rated passenger were fatally injured. The glider was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot and passenger were participating in a soaring competition when the accident occurred. Data from the glider’s PowerFLARM-IGS flight recorder indicated that the glider departed from Nephi Municipal Airport (U14), Nephi, Utah, at 1230:47. At 1238:19, the glider encountered its first thermal and gained another 2,158 ft in altitude. Over the next 40 minutes, the glider flew north, then east, during which time it encountered four different thermals and the pilot climbed 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; however, the glider continued to descend. The last recorded data point, at 1359:47, indicated that the glider was in a right turn was about 185 ft agl.
Figure 1. Accident Site Location METEOROLOGICAL INFORMATIONThe National Weather Service (NWS) 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-hectopascals (hPa) was located over southern Utah immediately south of the accident site, with a general high-pressure ridge extending over the state. The station models surrounding the accident site depicted clear skies, light wind of 5 knots, with temperatures in the upper 80’s to low 90’s degrees Fahrenheit (F).
A High-Resolution Rapid Refresh (HRRR) numerical model depicted an elevation of 7,431 ft, a surface temperature of 25.5°C (78° F), a dew point temperature of -3.0°C (27°F), a relative humidity of 15%, with a density altitude of about 10,016 ft. The sounding indicated support for strong thermal activity from the surface through 17,500 ft. The lifted condensation level was identified at 11,425 ft agl (18,856 ft msl) with the convective condensation level above that at 12,961 ft agl. The precipitable water content 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 indicated a surface wind from the southwest at 9 knots with winds backing to the south-southwest through 15,000 ft and then slowly veering to the southwest with height. The mean 0 to 6 kilometer or 18,000 ft wind was from 230° at 15 knots, and the maximum wind was identified at 40,000 ft from 220° at 53 knots.
GOES-17 visible satellite image for 1546 depicted clear skies over the accident site with fair weather cumulus clouds on the eastern slopes of the mountain range immediately east of the accident site. WRECKAGE AND IMPACT INFORMATIONThe wreckage was located in mountainous terrain about 4.25 miles northeast of Ephraim, Utah, at an elevation of 7,628 ft mean sea level, and was contained within a 50-ft area. The main wreckage included the left wing, cockpit, fuselage, empennage, and engine. The forward fuselage and cockpit area was 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 the majority of the outboard portion of the right wing were wrapped around the tree; the remaining outboard portion of the wing remained with the main wreckage. The right inboard section remained attached to the right outboard section; the right-wing tip had separated from the wing. The inboard and outboard ailerons remained attached to the wing. The left inboard wing remained attached to the fuselage. Fractures and deformations along the wingspan were consistent with impact forces. The outboard portion of the left wing was fractured and bent backwards. The inboard and outboard ailerons remained attached to the wing.
The steel fuselage truss was deformed and fractured in multiple places consistent with the fuselage damage. The fuselage shell fractured about halfway along its span; all flight control cables remained attached to their respective attach points.
The empennage was fractured from the fuselage just forward of the vertical stabilizer but remained attached by the control rods and cables. The vertical stabilizer was rotated 180° and its leading edge came to rest on the ground. The horizontal stabilizer remained attached to the top of the vertical stabilizer and was engaged with the forward and aft mount points. The elevator hinges were intact and undamaged. The rudder remained intact. The aileron controls were fractured and deformed in multiple places between the forward control stick and the tunnels, consistent with the extensive forward fuselage damage. All fractures observed in the flight controls had a dull, grainy appearance. Deformation was consistent with overstress separation. ADDITIONAL INFORMATIONThe FAA Glider Flying Handbook (FAA-H-8083-13A), states:
It is not uncommon for thermals to exist with slope lift…When a thermal is encountered along the ridge, a series of S-turns can be made into the wind. Drift back to the thermal after each turn if needed and, of course, never continue the turn to the point that the glider is turning toward the ridge. MEDICAL AND PATHOLOGICAL INFORMATIONThe Utah Department of Health, Office of the Medical Examiner, Taylorsville, Utah, performed an autopsy of the pilot and passenger. The cause of death for both was multiple blunt force injuries.
The Federal Aviation Administration (FAA) Forensic Sciences Laboratory conducted toxicology tests on specimens from the pilot and detected the previously-reported medications rosuvastatin, tadalafil, and lansoprazole.