# NTSB ANC91LA041: Bell 47, N73279, Thompson Pass, AK, March 30, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: March 30, 1991, 15:00 local (19:00 UTC)
- Place: Thompson Pass, AK
- Coordinates: 61.149665, -146.810668 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=61.1497&lon=-146.8107&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB office: Alaska Regional Office
- NTSB case key (mKey): 5530
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ANC91LA041
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/5530/pdf
- Page: https://openairdocs.org/ntsb/ANC91LA041

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN AIRCRAFT CONTROL AND IMPROPER FLARE DURING LANDING.

## Sequence of events

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

- Hard landing, landing - flare/touchdown
  - terrain condition - high terrain (contributing factor)
  - aircraft control - not maintained, pilot in command (cause)
  - flare - improper, pilot in command (cause)

## Analysis

ON FINAL APPROACH TO A MOUNTAIN RIDGE AT THE 5,000 FOOT LEVEL, THE HELICOPTER MADE A HARD LANDING.  AFTER GROUND IMPACT, THE MAIN ROTOR BLADES STRUCK THE TAIL BOOM CAUSING SUBSTANTIAL DAMAGE.

## Aircraft

- Registration: [N73279](https://openairdocs.org/aircraft/N73279), registered now, S/N 3134 (OpenAirDocs)
- Reported make and model: BELL 47
- Registry model: [Bell 47G-4](https://openairdocs.org/model/bell-47g-4) (registry code 1181030) (OpenAirDocs)
- Registry engine: [Lycoming VO-540 series](https://openairdocs.org/engine/lycoming-vo-540-series) (registry code 41534, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 3134
- Airframe hours: 3873
- Engines: LYCOMING VO-540-B1B3 260 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 24, 1991, 36 hours before
- Departed: NONE, THOMPSON PASS, AK
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; airplane ratings: single-engine sea, multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 5,420 total, 75 in this make and model, 5,110 as pilot in command, 5,350 in the last 90 days, 44 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 15 knots
- Visibility: 98 statute miles
- Lowest ceiling: none
- Temperature: 36 °F, dew point 19 °F
- Altimeter: 30.00 inHg

## 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 19910330007859A](https://openairdocs.org/incident/19910330007859A), Mar 30, 1991: Bell 47G4, Thompson Pass, AK, Substantial damage. Made hard landing on mountain ridge skid broke through crusted snow. Rotors damaged tail boom.

## Other investigations on N73279 (2)

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.

- [NTSB LAX92LA396](https://openairdocs.org/ntsb/LAX92LA396), Sep 21, 1992: Bell 47-G4A (N73279), Volcano, HI, substantial damage. Probable cause: THE PILOT'S IMPROPER USE OF THE COLLECTIVE CONTROL AFTER INADVERTENTLY ENTERING A POWER SETTLING CONDITION.
- [NTSB ANC76AA028](https://openairdocs.org/ntsb/ANC76AA028), Aug 27, 1975: Bell 47G-4 (N73279), Granite Mt., AK, substantial damage

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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