# NTSB DEN84LA139: Aerospatiale 316B, N608RM, Near Dillon, CO, April 29, 1984

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 29, 1984, 15:30 local (21:30 UTC)
- Place: Near Dillon, CO
- Coordinates: 39.620826, -106.029197 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.6208&lon=-106.0292&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): 16373
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84LA139
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16373/pdf
- Page: https://openairdocs.org/ntsb/DEN84LA139

## Sequence of events

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

- In flight encounter with weather, cruise
  - planning/decision - improper, pilot in command (cause)
  - terrain condition - high terrain (contributing factor)
  - weather condition - snow (contributing factor)
  - weather condition - unfavorable wind (contributing factor)
  - weather condition - downdraft (contributing factor)
- In flight collision with terrain/water, maneuvering
  - weather condition - high density altitude (contributing factor)
  - terrain condition - mountainous/hilly (contributing factor)
  - terrain condition - snow covered (contributing factor)
  - visual/aural detection, pilot in command (contributing factor)
  - terrain condition - uphill (contributing factor)

## Analysis

WHEN THE PLT TOOK OFF FROM A MOUNTAINOUS SKI AREA, LIGHT TO MODERATE SNOW WAS FALLING & THE WINDS WERE COMING UP THE VALLEY AT 5 TO 10 KTS. DURING THE FLT, HE ENCOUNTERED AN ESTIMATED 35 KT UPSLOPE WIND AS HE WAS PROCEEDING ON THE UPWIND SIDE OF A RIDGE AT AN ELEVATION OF ABOUT 12700 FT. WITH THE UPDRAFT, HE WAS ABLE TO REDUCE POWER. THE HORIZON WAS NOT VISIBLE BUT HE COULD SEE THE MOUNTAIN TO HIS LEFT REAR AREA. JUST PRIOR TO THE ACCIDENT, THE ACFT WAS TRAVELING AT ABOUT 40 KTS AT 100 TO 150 FT AGL. THE PLT STATED THAT WHILE HE WAS STILL IN AN UPDRAFT WITH REDUCED POWER, HE LOOKED BACK, NO MORE THAN 3 TO 5 SEC. AS HE LOOKED FORWARD AGAIN. HE ENCOUNTERED A WIND SHIFT WHICH PUT HIM IN A DOWNWIND, LOW POWER SITUATION. FEELING THERE WAS INSUFFICIENT SPACE TO TURN DOWNHILL, HE TURNED UPHILL, ADDED POWER & FLARED. THE HELICOPTER TOUCHED DOWN HARD ON STEEP TERRAIN AT ABOUT 12500 FT. THEN BECAME AIRBORNE AGAIN. IT IMPACTED AGAIN AFTER DROPPING 15 TO 25 FT & CAME TO REST. THE T/R & T/R GEAR BOX SEPARATED DURING THE SEQUENCE.

## Aircraft

- Registration: [N608RM](https://openairdocs.org/deregistered/N608RM-1988-11-30), registration cancelled 1988-11-30, S/N 1166 (OpenAirDocs)
- Reported make and model: AEROSPATIALE 316B
- Registry model: [Aerospatiale SE3160 ALOUETTE III](https://openairdocs.org/model/aerospatiale-se3160-alouette-iii) (registry code 8680605) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1166
- Airframe hours: 3455
- Engines: Turbomeca IIB 562 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Ferry, Part 91
- Operator: St. Anthony'S Hospital, doing business as [Ems]
- Registered owner: Rocky Mountain Helicopters
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, April 19, 1984
- Departed: DILLON, CO
- Destination: DEN, DENVER, CO

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; airline transport; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 5,300 total, 623 in this make and model, 2,500 as pilot in command, 32 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Day
- Wind: 90° at 30 knots, gusting 40
- Lowest ceiling: 700 ft overcast
- Temperature: 28 °F
- Altimeter: 29.00 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 19840429018059A](https://openairdocs.org/incident/19840429018059A), Apr 29, 1984: Aerosp SE3160, Dillon, CO, Substantial damage. Downdraft while low power setting near a ridge. Trapped. Made hard upslope landing. Impact cut off the tail boom.

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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