SEA99FA126 · Cessna T-337 G-P
Cessna T-337 G-P · Accident: in flight encounter with weather while maneuvering
From Lewistown Municipal Airport (LWT) to King County International Airport - Boeing Field (BFI)
Event
- NTSB case
- SEA99FA126
- 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
- Instrument Meteorological Cond
Cessna T-337 G-P
- Aircraft type
- Cessna T-337
- 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
- N98C
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lewistown Municipal Airport (LWT), Lewistown, MTTo King County International Airport - Boeing Field (BFI), Seattle, WA
- 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 › Clearance, not maintained
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While en route from Lewistown, Montana, to Olympia, Washington, on an instrument flight plan, the pilot developed a problem with the aircraft's autopilot and elected to cancel his instrument flight plan and proceed to Seattle, Washington, where repairs to the aircraft could be made. The pilot stated he was going to continue on his IFR flight plan until reaching Ellensburg, Washington, and then '...change to VFR and drop down and fly through the pass.' Approximately 30 minutes after the pilot canceled his IFR flight plan, a witness observed an aircraft 'with two tail fins' fly out of the clouds and proceed westbound along the Interstate Highway. The witness, who did not see the crash, also stated that the visibility was 100-300 feet, and the clouds were low to the ground. The aircraft collided with mountainous terrain approximately 25 miles east of Seattle, Washington.
Probable cause
The pilot's failure to maintain clearance from mountainous terrain while maneuvering below low ceilings. Factors include low ceilings and inadequate in-flight planning.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA99FA126
- Event ID
- 20001212X19360
- Case number
- SEA99FA126
- 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: 14d4154d3169e4f51da11f4b91b7f73afa2c659a3f1d8438a502f19078b29000; retrieved 2026-09-20T21:58:07.454Z.