SEA04LA095 · WSK PZL Mielec PZL M-18B
New Frontier Aviation WSK PZL Mielec PZL M-18B · Accident: in flight encounter with weather en route
From Dillon Airport (DLN) to Boise Air Terminal/Gowen Field (BOI)
Event
- NTSB case
- SEA04LA095
- 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
- 1 · 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
WSK PZL Mielec PZL M-18B
- Aircraft type
- WSK PZL Mielec PZL M-18B
- 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
- N117BS
- Operator
- New Frontier Aviation
- Onboard fatalities
- Unknown
- Route
- From Dillon Airport (DLN), Dillon, MTTo Boise Air Terminal/Gowen Field (BOI), Boise, ID
- 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
- 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
- Visual flight rules (VFR) flight into instrument meteorological conditions (IMC)
- 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 › Altitude/clearance, not obtained/maintained
- Pilot in command › In-flight planning/decision, inadequate
- Pilot in command › VFR flight into imc
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 was on the first leg of a visual flight rules (VFR) cross-country flight that originated approximately one hour and 15 minutes prior to the accident. After failing to arrive at the scheduled destination, the FAA issued an Alert Notice (ALNOT) and a search for the missing airplane was initiated. Eight days after the search was initiated, the missing airplane was located in mountainous terrain near the summit of Borah Peak at an elevation of approximately 11,210 feet above mean sea level. Widespread areas of instrument meteorological conditions (IMC) were reported along the pilot's route of flight. Weather forecasts for the time and area of the accident included icing conditions and mountain obscuration.
Probable cause
The pilot's inadequate planning/decision, VFR into IMC, and his failure to maintain terrain clearance. Factors include mountainous terrain and instrument meteorological condition.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA04LA095
- Event ID
- 20040608X00749
- Case number
- SEA04LA095
- 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: c9085e22ecf44929b5f34179a2e48cfc7f73cedf63b67bbd531d22e4de35c561; retrieved 2026-09-20T18:28:33.553Z.