# NTSB DEN84LA079: Bell 47G-3B-1, N90769, Ogden, UT, January 31, 1984

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 30, 1984, 17:10 local (Jan 31, 1984, 00:10 UTC)
- Place: Ogden, UT
- Location: 41.2284° N, 111.9681° W: Placed by OpenAirDocs: center of Ogden, UT, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.2284&lon=-111.9681&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16328
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84LA079
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16328/pdf
- Page: https://openairdocs.org/ntsb/DEN84LA079

## Sequence of events

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

- In flight encounter with weather, cruise
  - weather condition - fog (contributing factor)
  - weather condition - obscuration (contributing factor)
  - terrain condition - snow covered (contributing factor)
  - weather condition - whiteout (contributing factor)
  - vfr flight into imc - continued, pilot in command (cause)
- Loss of control - in flight, hover
  - aircraft handling - not maintained, pilot in command (cause)
  - spatial disorientation, pilot in command (cause)
- Roll over, landing

## Analysis

THE PLT TOOK OFF FROM A MOUNTAINOUS WORK SITE TO RETURN TO SALT LAKE CITY, UT. THE WX WAS CLEAR AT THE WORK SITE (ELEVATION 6700 FT), BUT THERE WAS FOG BELOW. AFTER ENCOUNTERING THE FOG, THE PLT HOVERED WITH A SLOW FORWARD SPEED OVER SNOW COVERED TERRAIN. A PASSENGER SAID THAT WHERE ROCKS PROTRUDED THRU THE SNOW, THEY PROVIDE A REFERENCE, THEN SUDDENLY THERE WERE NO ROCKS. AS THE HELICOPTER PROCEEDED OVER AN OPEN AREA, THE PLT LOST GROUND RECERENCES. HE SAID HE MAY HAVE EXPERIENCED VERTIGO BECAUSE HE THOUGHT HE WAS ABOUT ON THE GROUND WHEN THE HELICOPTER HIT & ROLLED OVER. THE ELEVATION AT THE CRASH SITE WAS ABOUT 5000 FT.

## Aircraft

- Registration: [N90769](https://openairdocs.org/deregistered/N90769-2013-07-09), registration cancelled 2013-07-09, S/N 2901, built 1963 (OpenAirDocs)
- Reported make and model: BELL 47G-3B-1
- Registry model: [Bell 47G-3B-1](https://openairdocs.org/model/bell-47g-3b-1) (registry code 1181028) (OpenAirDocs)
- Registry engine: [Lycoming TVO-435-GIA](https://openairdocs.org/engine/lycoming-tvo-435-gia) (registry code 41526, turbo-prop) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2901
- Airframe hours: 4829
- Engines: LYCOMING TVO-435-B1A 270 horsepower reciprocating
- Damage: Substantial damage
- Fire: On-Ground
- Flight: Part 135
- Registered owner: Didericksen
- Airworthiness certificate: Standard, Normal
- Departed: NEAR OGDEN, UT

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 42; airline transport; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 5,204 total, 1,350 in this make and model, 4,776 as pilot in command, 153 in the last 90 days, 58 in the last 30 days

## Weather

- Conditions: Instrument (IMC), Day
- Wind: calm
- Temperature: 19 °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 19840130002939A](https://openairdocs.org/incident/19840130002939A), Jan 30, 1984: Bell 47G3B1, Ogden, UT, Substantial damage. Encountered dense fog slowed to a hover lost ground reference. Backed up into rocks and rolled over.

## Other investigations on N90769 (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 SEA78DTA18](https://openairdocs.org/ntsb/SEA78DTA18), Aug 20, 1978: Bell 47G3B1 (N90769), Billings, MT, substantial damage
- [NTSB DEN76FTE18](https://openairdocs.org/ntsb/DEN76FTE18), Aug 24, 1975: Bell 47G3B1 (N90769), Denver, CO, 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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