# NTSB SEA91FA046: Cessna C-172, N8531B, Colstrip, MT, February 3, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: February 2, 1991, 19:45 local (Feb 3, 1991, 02:45 UTC)
- Place: Colstrip, MT
- Coordinates: 45.97977, -106.670768 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.9798&lon=-106.6708&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report January 25, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 41302
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91FA046
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41302/pdf
- Page: https://openairdocs.org/ntsb/SEA91FA046

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN ADEQUATE TERRAIN CLEARANCE.  FACTORS RELATING TO THE ACCIDENT WERE THE PILOT'S LACK OF TOTAL NIGHT FLIGHT EXPERIENCE, HIS LACK OF RECENT NIGHT FLIGHT EXPERIENCE, THE DARK NIGHT LIGHT CONDITIONS, AND THE MOUNTAINOUS/HILLY TERRAIN IN THE AREA.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- In flight collision with terrain/water, approach - vfr pattern - downwind
  - light condition - dark night (contributing factor)
  - clearance - not maintained, pilot in command (cause)
  - lack of total experience in type operation, pilot in command (contributing factor)
  - terrain condition - mountainous/hilly (contributing factor)
  - lack of recent experience in type operation, pilot in command (contributing factor)

## Analysis

THE ACFT IMPACTED A RIDGELINE ON DOWNWIND IN THE TRAFFIC PATTERN WHILE THE PILOT WAS ON A NIGHT CURRENCY TRAINING FLIGHT AT A RECENTLY OPENED LIGHTED AIRPORT.  THE PILOT HAD 4 HOURS TOTAL NIGHT FLIGHT TIME, WITH .8 HOURS PIC, ALL FLOWN DURING INITIAL PILOT TRAINING IN 1984.  HE HAD NO RECORDED NIGHT FLIGHT TIME SINCE.  HE WAS NOT INSTRUMENT RATED AND HAD NO INSTRUMENT FLIGHT TIME.  THE AIRPORT IS LOCATED IN AN UNPOPULATED MOUNTAINOUS AREA WITH VERY LITTLE ARTIFICIAL LIGHT.  THERE WAS NO NATURAL ILLUMINATION AT THE TIME OF THE ACCIDENT.

## Aircraft

- Registration: [N8531B](https://openairdocs.org/deregistered/N8531B-1991-03-22), registration cancelled 1991-03-22, S/N 36231 (OpenAirDocs)
- Reported make and model: CESSNA C-172
- Registry model: [Cessna 172](https://openairdocs.org/model/cessna-172) (registry code 2072402) (OpenAirDocs)
- Category: Airplane
- Serial number: 17236231
- Engines: CONTINENTAL O-300-D 145 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: John E. Ricks
- Registered owner: John E. Ricks
- Departed: M46, COLSTRIP, MT
- Airport: M46, Colstrip, runway 24, 5,100 × 75 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 56; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; toxicology performed; flight hours: 279 total, 153 in this make and model, 220 as pilot in command, 7 in the last 90 days, 2 in the last 30 days

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 180° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 36 °F, dew point 27 °F
- Observed at: MLS, 49 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19910202001499A](https://openairdocs.org/incident/19910202001499A), Feb 2, 1991: Cessna 172, Colstrip, MT, Destroyed, 2 fatal. Flying too low at night flew into side of unlighted hill. Had no recent night check out or recent night time.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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