NTSB CAROL · Event
Event CEN20CA326
Aircraft involved
Probable cause & findings
The flight instructor's failure to maintain helicopter control which resulted in a hard landing while preforming a practice autorotation.
Factual narrative
The instructor reported that during the instructional flight, he was manipulating the controls and accepted the option to land on the taxiway; he decreased the throttle for a full touchdown auto rotation. About 50 ft above the ground (agl), he flared the helicopter and leveled off about 5 to 10 ft agl. The instructor reported that everything seemed "normal" at this point. He then raised the collective, but the descent was not arrested, so he raised the collective full up. The helicopter landed hard and shook violently. The instructor closed the throttle to which stopped the fuel supply. The tailboom was substantially damaged. The flight instructor reported that there were no mechanical anomalies with the helicopter that would have precluded normal operation. The instructor added that he felt a slight tailwind after exiting the helicopter and that the tail wind caused a "vortex ring state" which stalled the main rotor blades. 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).
- C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Descent rate-Capability exceeded - C
- — Personnel issues-Task performance-Use of equip/info-Aircraft control-Instructor/check pilot
- — Environmental issues-Conditions/weather/phenomena-Wind-Tailwind-Effect on operation
Verbatim from NTSB's published report. Source file
NTSB_2020_CEN20CA326.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…
Browse the full corpus — academia portal ↗