# NTSB ANC90LA080: Interstate S1B1, N55AD, Beluga River, AK, May 26, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: May 25, 1990, 18:30 local (May 26, 1990, 02:30 UTC)
- Place: Beluga River, AK
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report August 28, 1992
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5373
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC90LA080
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5373/pdf
- Page: https://openairdocs.org/ntsb/ANC90LA080

## Probable cause

THE PILOT SELECTED UNSUITABLE TERRAIN. CONTRIBUTING FACTORS WERE THE SOFT TERRAIN AND THE PILOT'S LACK OF EXPERIENCE IN OFF-AIRPORT OPERATIONS.

## Analysis

THE PILOT REPORTED THAT HE WAS MAKING HIS SECOND LANDING AT A SANDBAR DURING A FISHING TRIP. HE SAID THAT HE WAS SEEKING A BETTER LANDING SITE PRIOR TO BRINGING ANOTHER PASSENGER TO THE SANDBAR. DURING THE LANDING ROLL THE MAIN LANDING GEAR ENCOUNTERED A SOFT SPOT AND THE AIRPLANE NOSED OVER.

## Sequence of events

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

- Nose over, landing - roll
  - terrain condition - soft (contributing factor)
  - unsuitable terrain or takeoff/landing/taxi area - selected, pilot in command (cause)
  - lack of total experience in type operation, pilot in command (contributing factor)

## Aircraft

- Registration: [N55AD](https://openairdocs.org/aircraft/N55AD), registered now, S/N 1006, built 1977 (OpenAirDocs)
- Reported make and model: INTERSTATE S1B1
- Registry model: [Arctic S-1B2](https://openairdocs.org/model/arctic-s-1b2) (registry code 0790208) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 1006
- Engines: LYCOMING O-320 150 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Ferguson, James L
- Registered owner: Ferguson, James L
- Airport: NONE

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; flight hours: 152 total, 79 in this make and model, 152 as pilot in command, 49 in the last 90 days, 27 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: variable at 5 knots, gusting 10
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 61 °F, dew point -0 °F

## 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 19900525018259A](https://openairdocs.org/incident/19900525018259A), May 25, 1990: Arctic S1B2, Beluga River, AK, Substantial damage. Landing on a sandbar wheel hit a soft spot. Aircraft nosed over. Bent lift struts.

## Other investigations on N55AD (2)

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

- [NTSB ANC04LA045](https://openairdocs.org/ntsb/ANC04LA045), Apr 23, 2004: Arctic S-1B2 (N55AD), Big Lake, AK, substantial damage. Probable cause: The flight instructor's failure to insure that the carburetor heat was activated by the dual student following a simulated loss of engine power, which resulted in carburetor ice and the actual loss…
- [NTSB ANC88LA116](https://openairdocs.org/ntsb/ANC88LA116), Aug 24, 1988: Artic S-1B2 (N55AD), Hartman River, AK, substantial damage

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

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