SEA92FA154 · Beech 58
Beech 58 · Accident: in flight encounter with weather while maneuvering
From Boise Air Terminal/Gowen Field (BOI) to Glacier Park International Airport (FCA)
Event
- NTSB case
- SEA92FA154
- 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
- 2 · all aircraft and ground
- Ground fatalities
- 0
- 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
- Unknown
Beech 58
- Aircraft type
- Beechcraft 58
- 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
- N23LB
- Operator
- Sinclair, Richard C. · private individual
- Onboard fatalities
- Unknown
- Route
- From Boise Air Terminal/Gowen Field (BOI), Boise, IDTo Glacier Park International Airport (FCA), Kalispell, 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
- Maneuvering
- 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 › Aircraft control, not maintained
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
PRIOR TO TAKEOFF, THE PILOT OBTAINED A WEATHER BRIEFING AND WAS INFORMED OF MOUNTAIN OBSCUREMENT, RAIN SHOWERS, AND THUNDERSTORM ACTIVITY IN THE AREA OF THE FLIGHT PATH. THE PILOT HAD FILED THE ROUTE OF FLIGHT DIRECT FROM BOISE, ID, TO MCCALL, ID, TO THOMPSON FALLS, MT, TO KALISPELL, MT. THE ACCIDENT SITE WAS LOCATED APPROXIMATELY 45 MILES EAST OF THE DIRECT LINE OF FLIGHT PATH IN MOUNTAINOUS TERRAIN. RADAR DATA IDENTIFIES THE FLIGHT AS MANEUVERING ON VARIOUS HEADINGS BEFORE THE FLIGHT DROPPED FROM RADAR CONTACT. THE WRECKAGE WAS FOUND CONFINED TO A DEEP CRATER WITH THE NOSE OF THE AIRPLANE AT THE CRATER'S DEEPEST POINT. IT WAS ESTIMATED THAT THE AIRPLANE COLLIDED WITH THE TERRAIN IN AN APPROXIMATE 70 DEGREE NOSE DOWN ATTITUDE. THERE WAS NO EVIDENCE FOUND TO INDICATE A MECHANICAL FAILURE OR MALFUNCTION.
Probable cause
INFLIGHT LOSS OF CONTROL WHEN AIRCRAFT CONTROL WAS NOT MAINTAINED. FACTORS TO THE ACCIDENT WERE: FLIGHT INTO KNOWN ADVERSE WEATHER AND THUNDERSTORM ACTIVITY.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA92FA154
- Event ID
- 20001211X15243
- Case number
- SEA92FA154
- 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. 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: 3816549b6ddb7c577f87805811c1b6168cc0aa4bd7368d5cf765643e8dc4373c; retrieved 2026-09-21T01:03:10.380Z.