SEA98LA185 · Duncan DX4
Duncan DX4 · Accident: in flight collision with terrain/water on approach
From Priest River Municipal Airport (1S6) to an unrecorded destination
Event
- NTSB case
- SEA98LA185
- 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
- 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
- Visual Meteorological Cond
Duncan DX4
- Aircraft type
- Duncan DX4
- 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
- N4DX
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Priest River Municipal Airport (1S6)To not recorded
- 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
- Approach · VFR pattern turn to base
- 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 collision with terrain/water
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Stall/mush
- 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
- Pilot in command › Airspeed(vs), inadequate
- Pilot in command › Stall/mush, inadvertent
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
After turning downwind in the experimental aircraft, the pilot sensed that the lateral flight controls were not responding to his inputs as he thought they would. He therefore elected to continue around the pattern and land. Because he felt that a reduction in power positively effected the perceived control problem, he reduced power on downwind and then attempted to turn base. Witnesses said that the aircraft was going very slow prior to turning base, and that as it entered a left bank, it fell out of the sky. Just prior to impacting the ground, the aircraft rolled wings-level. No problem with the lateral flight control system was able to be identified, and no reason for the perceived lateral control anomaly was determined.
Probable cause
The pilot's failure to maintain adequate airspeed which resulted in a stall/mush. Factors include allowing his attention to be diverted by what he perceived to be a lateral control problem.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA98LA185
- Event ID
- 20001211X11175
- Case number
- SEA98LA185
- 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: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1998-09-22.
- API snapshot SHA-256: 43513f7328552c9210a9dce9b6722fe55eb15981e9746d0d40d0779fd99e23b2; retrieved 2026-09-21T11:20:15.669Z.