NTSB CAROL · Event
Event WPR21LA212
Registry · N9254E
FAA Aircraft Registry record.
Make / Model
MAULE M-5-235C
Engine
LYCOMING 0-540 SERIES (250 hp)
Seats / Engines
4 seats · 1 engine
Last airworthiness date
19771028
ADS-B equipped
Yes — Mode-S ACD3A6
Registrant of record
MOORE THOMAS R
Source: FAA Aircraft Registry (releasable master file).
Aircraft involved
Probable cause & findings
The pilot’s failure to use carburetor heat in weather conditions conducive to carburetor icing, resulting in a partial loss of engine power and a forced landing during which the airplane struck an object and nosed over.
Factual narrative
On May 29, 2021, about 1100 mountain daylight time, a Maule M-5-235C, N9254E, was substantially damaged when it was involved in an accident near Thomas Creek Airport (2U8), Stanley, Idaho. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 flight. The pilot reported that the airplane’s takeoff and climb from Johnson Creek Airport (3U2), Yellow Pine, Idaho, about 30 minutes before the accident, was uneventful. When the airplane reached an altitude of about 10,000 ft mean sea level (msl), the pilot reduced engine power and initiated a descent to 2U8, with the intention of performing a low approach to check the runway surface then landing if conditions allowed. About 500 ft before the runway threshold, the pilot applied full engine power, and the engine responded but then began to progressively lose power. He turned on the carburetor heat, confirmed that the engine mixture was set correctly, and began to turn the airplane away from rising terrain at the end of the runway. The airplane would not climb, and the pilot maneuvered the airplane through a neighboring canyon, at which time the engine started to regain power. The pilot continued to assess the surrounding terrain and decided that he would not be able to safely turn the airplane around. He then observed a flat area and maneuvered the airplane to that spot to perform a forced landing at the lowest possible airspeed. During the landing flare, the airplane struck a log and nosed over. Postaccident examination revealed no anomalies with the engine that would have precluded normal operation. The closest official weather observation station, located at McCall Municipal Airport, McCall, Idaho, indicated a temperature and a dew point temperature of about 44.5°F and 37.5 F, respectively, about the time of the accident. According to Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, such conditions were conducive to serious carburetor icing at cruise power. The pilot initiated a descent to the remote airstrip with the intention of performing a low approach to check the runway surface then landing if conditions allowed. About 500 ft before the runway threshold, the pilot applied full engine power, and the engine responded but then began to progressively lose power. He turned on the carburetor heat, confirmed that the engine mixture was set correctly, and began to turn the airplane away from rising terrain. The airplane would not climb, and he maneuvered it through an adjacent canyon, at which time the engine started to regain power. Due to rising terrain, the pilot had limited options to turn around the airplane, so the pilot performed a forced landing. During the landing flare, the airplane struck a log and nosed over. Postaccident examination revealed no anomalies with the engine that would have precluded normal operation. Weather conditions at the time of the flight were conducive to serious carburetor icing at cruise power. The pilot did not turn on carburetor heat until after the engine started to lose power, so it is likely that pilot’s failure to use carburetor heat earlier in the flight caused carburetor icing that led to the partial loss of engine power. 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).
- — Environmental issues-Conditions/weather/phenomena-Temp/humidity/pressure-Conducive to carburetor icing-Effect on equipment
- — Personnel issues-Action/decision-Action-Delayed action-Pilot
- — Aircraft-Aircraft systems-Ice/rain protection system-Intake anti-ice, deice-Not used/operated
Verbatim from NTSB's published report. Source file
NTSB_2021_WPR21LA212.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 ↗