SEA98FA100 · Aero Commander 680FL
Aero Commander 680FL · Accident: in flight collision with terrain/water on approach
From Glacier Park International Airport (FCA) to Helena Regional Airport (HLN)
Event
- NTSB case
- SEA98FA100
- 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
- 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
- Charter & commuter
- 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
Aero Commander 680FL
- Aircraft type
- Aero Commander 680
- 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
- N446JR
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Glacier Park International Airport (FCA), KALLISPELL, MTTo Helena Regional Airport (HLN), Helena, 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 135: Air Taxi & Commuter
- 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 · IFR initial approach
- 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
- 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 › Proper altitude, not maintained
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot of the Part 135 cargo flight was executing the 'full' ILS runway 27 approach at Helena Regional Airport in a non-radar environment. Although the approach calls for the pilot to maintain 7,000 feet until intercepting the glideslope, the aircraft impacted the terrain at 5,300 about 1.5 miles prior to reaching the point where the pilot should have crossed the Hauser NDB at an altitude of 6,741 feet. According to the approach plate, the aircraft should not have descended to an altitude below 5,400 feet until reaching the outer marker, which is located about five and one-half miles west of the impact site.
Probable cause
The pilot's failure to maintain the correct altitude while turning inbound during a procedure turn to the ILS final approach course. Factors include hilly/mountainous terrain and clouds in the area where the course reversal was performed.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA98FA100
- Event ID
- 20001211X10417
- Case number
- SEA98FA100
- 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 1998-06-17.
- API snapshot SHA-256: 1b2c0085654067e5dde5ce8c5cf35fe040d4b8467ad094b1ebffc8feaf5d3fed; retrieved 2026-09-18T13:23:11.626Z.