NTSB CAROL · Event
Event CHI91LA205
Registry · N94515
FAA Aircraft Registry record.
Make / Model
HILLER UH-12D
TCDS
4H10 · SIAM HILLER HOLDINGS INC
Engine
LYCOMING VO-435 SERIES (260 hp)
Seats / Engines
4 seats · 1 engine
Last airworthiness date
19780411
ADS-B equipped
Yes — Mode-S AD2254
Registrant of record
HILLER AIRCRAFT CORP
Source: FAA Aircraft Registry (releasable master file).
Aircraft involved
Probable cause & findings
THE PILOT'S FAILURE TO MAINTAIN TAIL ROTOR CLEARANCE FROM THE GROUND. A RELATED FACTOR IS THE PILOT'S LACK OF TOTAL EXPERIENCE IN HELICOPTERS.
Factual narrative
THE COMMERCIAL AIRPLANE PILOT WAS PERFORMING 'QUICK STOP' MANEUVERS WHILE PRACTICING FOR HIS HELICOPTER RATING. HE REPORTED THAT HE ENTERED THE MANEUVER AT 20 FEET ABOVE THE GROUND, THEN MADE SEVERAL ADJUSTMENTS WITH BOTH CYCLIC AND COLLECTIVE IN AN ATTEMPT TO MAINTAIN ROTOR RPM AND ALTITUDE. THE HELICOPTER DESCENDED DURING THE MANEUVER AND THE TAIL ROTOR STRUCK THE GROUND. THE PILOT STATED THAT HE BEGAN TO LOSE DIRECTIONAL CONTROL AFTER THE TAIL ROTOR GROUND CONTACT, SO HE REDUCED COLLECTIVE AND MADE A HARD LANDING ON THE GRASS ADJACENT TO THE RUNWAY. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12
Verbatim from NTSB's published report. Source file
NTSB_1991_CHI91LA205.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 (icing). 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 · Contractor Report (CR)
Icing Physics Studies Using the 3D SIDRM Test Article: 2023 Icing Tests Analysis
In-flight icing is an important safety issue and is a factor that affects aircraft design and performance. Newer regulations are driving a need for improvements in airframe and engine icing simulation…
- arXiv 2025 · arXiv preprint
Multi-Agent Deep Reinforcement Learning for UAV-Assisted 5G Network Slicing: A Comparative Study of MAPPO, MADDPG, and MADQN
The growing demand for robust, scalable wireless networks in the 5G-and-beyond era has led to the deployment of Unmanned Aerial Vehicles (UAVs) as mobile base stations to enhance coverage in dense urb…
- Embry-Riddle Scholarly Commons 2025 · Journal article (JAAER)
A Mathematical Model on the Temporal Dynamics of Aviation Competitive Pricing
This study investigates the competitive dynamics of airport pricing using U.S. airport data to validate the findings. It employs linear and nonlinear ordinary differential equation models to analyze t…
- NASA NTRS 2025 · Presentation
NASA Icing Update – March 2025
This NASA Icing Update was prepared for presentation to the SAE International AC-9C Inflight Icing Technology Committee. This update includes the following topics: planned Rotational Icing Scaling tes…
- arXiv 2024 · arXiv preprint
An energy-stable phase-field model for droplet icing simulations
A phase-field model for three-phase flows is established by combining the Navier-Stokes (NS) and the energy equations, with the Allen-Cahn (AC) and Cahn-Hilliard (CH) equations and is demonstrated ana…
- NASA NTRS 2024 · Presentation
NASA Icing Update – Oct 2024
This presentation provides a status update on select NASA icing research activities for the SAE AC-9C Icing Technical Committee Meeting on Oct 21, 2024.
Browse the full corpus — academia portal ↗