DEN04FA079 · Mooney M20K
Mooney M20K · Accident: in flight encounter with weather en route
From Sunriver Airport (S21) to Central Wyoming Regional Airport (RIW)
Event
- NTSB case
- DEN04FA079
- 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
- 3 · 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
Mooney M20K
- Aircraft type
- Mooney M20
- 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
- N231DL
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Sunriver Airport (S21), Sunrise, ORTo Central Wyoming Regional Airport (RIW), Riverton, WY
- 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 · cruise
- 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
- In flight encounter with weather
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Pilot in command › Clearance, not maintained
- Pilot in command › Flight into adverse weather, inadvertent
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The non-instrument rated private pilot had been airborne for approximately 3 hours when he approached the Wind River Range in central Wyoming. Radar data indicated that he descended from 15,500 feet to 14,300 feet (because of weather) to cross the continental divide at Gannett Peak, elevation 13,804 feet,. Radar data indicates that approximately 20 seconds later, the airplane was in an approximate 4,200 feet per minute rate of descent. Satellite imagery and NEXRAD Doppler data suggest that at the pilot's ground track location, the mountain was experiencing light to intermittent snow showers according to the NTSB meteorologist. No endorsements could be found in the pilot's flight logbook to indicate that he had received any mountain flying training. Search and rescue teams found the airplane 3 days later. No evidence of a mechanical failure was found.
Probable cause
The pilot's inadvertent flight into adverse weather conditions, and his failure to maintain terrain clearance while maneuvering. Contributing factors were the downdraft, the snow shower weather and mountainous terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN04FA079
- Event ID
- 20040528X00684
- Case number
- DEN04FA079
- 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: e360a4ef47d327aa51e5daf1d2bd4e6b8500419496f28473aeb8fea8e00bcae3; retrieved 2026-09-20T18:28:23.161Z.