NTSB CAROL · Event
Event ERA21FA239
Aircraft involved
Probable cause & findings
The pilot’s low-altitude release from tow for reasons that could not be determined, and his subsequent exceedance of the glider’s critical angle of attack while returning to the runway, which resulted in an aerodynamic stall and impact with terrain.
Factual narrative
HISTORY OF FLIGHTOn June 6, 2021, about 1249 eastern daylight time, a Schweizer SGS 1-35 glider, N2878H, was substantially damaged when it was involved in an accident near Wurtsboro, New York. The private pilot was fatally injured. The glider was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the towplane pilot, the accident pilot owned the glider, and the accident flight was his first flight in the glider. The wing runner who helped launch the glider reported that the accident pilot stated that he was hesitant, as it was his first flight in the glider. During initial climb from runway 23, about 100 to 200 ft above ground level (agl), the glider pilot released the tow rope and began a 45° bank right turn back toward the airport. About 90° through the turn, the nose dropped straight down. The glider started to pull up but was still about 60° nose down when it impacted a ramp area, slid across a taxiway, and came to rest on a grass area between the taxiway and runway. A different pilot flew the accident glider the previous day and reported that it flew well. WRECKAGE AND IMPACT INFORMATIONThe glider came to rest upright, oriented south, about 100 feet east of the initial impact point. The wings and empennage remained attached, while the fuselage partially separated in a downward direction, just aft of the wings. The cockpit area was crushed, and the control stick separated consistent with impact forces. The canopy frame remained attached to the fuselage, but the windscreen had shattered. Flight control continuity was established from the cockpit to the flaps, ailerons, elevator, and rudder. The preimpact position of the flaps could not be determined. The tow release mechanism functioned normally when tested. The tow rope and its attachment hardware were intact. ADDITIONAL INFORMATIONReview of data downloaded from an onboard device revealed that the accident flight, including the tow, lasted about 1 minute. The glider was towed for approximately 45 seconds until it released at 1248:51.0 while in a 25° right turn about 170 ft agl over the runway 23 departure end. The glider stalled approximately 1.4 seconds later, at 1248:52.4 and impacted airport property about 1249:5.0. MEDICAL AND PATHOLOGICAL INFORMATIONAn autopsy was performed on the pilot by the Westchester County Medical Examiner’s Office, Valhalla, New York. The cause of death was multiple blunt force injuries. Toxicology testing performed by the Federal Aviation Administration (FAA) Bioaeronautical Sciences Laboratory. The testing detected the sedating antihistamine diphenhydramine in the pilot’s cardiac blood at 112 nanograms per milliliter (ng/mL) and in his urine. The anesthetic drug ketamine and its metabolite, norketamine, were detected in the pilot’s cardiac blood and urine; ketamine is used in resuscitation. Ibuprofen, commonly marketed as Advil, was also detected in the pilot’s cardiac blood and urine. Diphenhydramine is a sedating antihistamine (commonly marketed as Benadryl) and is available over the counter in many products used to treat colds, allergies, and insomnia. Diphenhydramine carries the warning that use of the medication may impair mental and physical ability to perform potentially hazardous tasks, including driving or operating heavy machinery. The therapeutic range is 25 to 100 ng/mL, and it has a half-life of 3 to 4 hours. Diphenhydramine undergoes postmortem distribution and central levels may be two to three times higher than peripheral levels. FAA provides guidance on wait times before flying after using this medication; post-dose observation time is 60 hours, and the medication is not for daily use. The accident flight was the pilot’s first flight in the glider make/model, and he indicated to the wing runner that he was “hesitant” about the flight. Witness statements and recorded data indicated that, just after takeoff, the glider released from the tow plane about 170 ft above ground level, while in a 25° right turn over the runway departure end. The glider continued the right turn and stalled about 1.4 seconds later, impacting airport property 13 seconds after the stall. Examination of the wreckage did not reveal any preimpact mechanical malfunctions. Toxicology testing revealed the presence of the sedating antihistamine diphenhydramine in cardiac blood and urine, indicating that the pilot had taken some allergy, cold, or sleep-aid medication before the accident. Even considering two-to-three-fold postmortem redistribution of diphenhydramine, the concentration in the pilot’s blood appeared to be at therapeutic levels. Compared to other antihistamines, diphenhydramine causes marked sedation; impaired cognitive and psychomotor performance may also be observed. While the impairing medication diphenhydramine was detected, it is unlikely that the effects from the pilot’s use of diphenhydramine contributed to this accident. Although the reason for the pilot’s release from tow at low altitude could not be determined, the accident is consistent with his failure to maintain airspeed during the turn back to the runway, which resulted in an aerodynamic stall and impact with terrain. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12
NTSB Findings
Hierarchical cause / factor breakdown from the FAA bulk avdata database. Each finding tagged C (Cause) or F (Factor).
- — Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot
- — Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Angle of attack-Capability exceeded
- — Personnel issues-Experience/knowledge-Experience/qualifications-Total experience w/ equipment-Pilot
Verbatim from NTSB's published report. Source file
NTSB_2021_ERA21FA239.txt.
Findings + structured fields enriched from FAA avall.mdb.
Full investigation docket on
data.ntsb.gov ↗.
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Related research
What the literature says.
Academic papers and agency reports matching this event's aircraft type or causal vocabulary (stall). Sourced from NASA NTRS, NTSB Safety Studies, FAA CAMI, AOPA Air Safety Institute, Embry-Riddle Scholarly Commons, arXiv, and the Semantic Scholar academic graph.
- NASA NTRS 2026 · Conference Paper
Computational Analysis of Steady State Aerodynamics of Transonic Truss-Braced Wing Configuration in Deep Stall
This study presents a computational investigation of steady state aerodynamics of the Subsonic Ultra-Green Aircraft Research (SUGAR) Transonic Truss-Braced Wing (TTBW) configuration over a wide range …
- arXiv 2023 · arXiv preprint
Automating Bird Diverter Installation through Multi-Aerial Robots and Signal Temporal Logic Specifications
This paper tackles the task assignment and trajectory generation problem for bird diverter installation using a fleet of multi-rotors.
- arXiv 2023 · arXiv preprint
Variation of Critical Crystallization Pressure for the Formation of Square Ice in Graphene Nanocapillaries
Two-dimensional square ice in graphene nanocapillaries at room temperature is a fascinating phenomenon and has been confirmed experimentally.
- arXiv 2023 · arXiv preprint
Polycrystallinity enhances stress build-up around ice
Damage caused by freezing wet, porous materials is a widespread problem, but is hard to predict or control. Here, we show that polycrystallinity makes a great difference to the stress build-up process…
- arXiv 2022 · arXiv preprint
Enhanced Prediction of Three-dimensional Finite Iced Wing Separated Flow Near Stall
Icing on three-dimensional wings causes severe flow separation near stall. Standard improved delayed detached eddy simulation (IDDES) is unable to correctly predict the separating reattaching flow due…
- Embry-Riddle Scholarly Commons 2021 · Journal article (JAAER)
Analysis on the Negative Emotional, Physiological, and Cognitive Responses Elicited from of the Activation of a Stall Alarm
Failing to identify an aerodynamic stall can lead to the inability of an aircraft to sustain flight. To warn pilots of an impending or fully-developed stall, many aircraft have safety devices installe…
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