SEA03LA097 · Cessna 172H
Cessna 172H · Accident: total loss of engine power (non-mechanical) en route
From Ione Municipal Airport (S23) to Glasgow Valley County Airport Wokal Field (GGW)
Event
- NTSB case
- SEA03LA097
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Cessna 172H
- Aircraft type
- Cessna 172
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N2786L
- Operator
- Grenfell, David L. · private individual
- Onboard fatalities
- Unknown
- Route
- From Ione Municipal Airport (S23), Ione, WATo Glasgow Valley County Airport Wokal Field (GGW), Glasgow, MT
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · descent
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Total loss of engine power (non-mechanical)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Fuel system, carburetor › Ice
- Pilot in command › Throttle/power control, reduced
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot of the carburetor equipped Cessna 172H was approximately 9 nautical miles west of his first fuel stop and commenced a let down through a hole in a broken cloud layer. The surface weather observation at his intended destination recorded several minutes after the accident reported two broken cloud layers at 2,600 feet and 3,400 feet, an overcast cloud layer at 7,000 feet, and temperature 53 degrees F. and dew point 45 degrees F. He reported applying carburetor heat and reducing engine RPM, and then having to descend faster and reduce engine RPM further. He continued a "gliding" descent to 4,000 feet and then re-applied power with no effect. He then executed a forced landing to a muddy, wet agricultural field during which the nose gear collapsed and the aircraft nosed over. FAA Advisory Circular 61-23B, "Pilot's Handbook of Aeronautical Knowledge," provides guidance for operations in carburetor icing conditions. Specifically, the reference states in part "... carburetor heat should be turned to "full-on" before closing the throttle, and left on during the closed-throttle operation...." and "...Periodically, however, the throttle should be opened smoothly for a few seconds to keep the engine warm, otherwise the carburetor heater may not provide enough heat to prevent icing...."
Probable cause
A loss of engine power due to carburetor icing. Contributing factors were carburetor icing conditions and the muddy, wet terrain at the landing site.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA03LA097
- Event ID
- 20030610X00840
- Case number
- SEA03LA097
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 3c2120f29100a2d5f0d0fb1c2b63a5aa6728d52139a950b6eb32c92e8d5c98b5; retrieved 2026-09-22T09:11:38.143Z.