# NTSB DEN85LTM05: Interstate S-1A, N37438, Rock Springs, WY, August 1, 1985

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Final report
- Date: August 1, 1985, 15:20 local (21:20 UTC)
- Place: Rock Springs, WY
- Coordinates: 41.589874, -109.220069 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.5899&lon=-109.2201&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16787
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85LTM05
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16787/pdf
- Page: https://openairdocs.org/ntsb/DEN85LTM05

## Sequence of events

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

- In flight encounter with weather, cruise - normal
  - in-flight planning/decision - improper, pilot in command (cause)
  - terrain condition - high terrain (contributing factor)
  - weather condition - high density altitude (contributing factor)
  - weather condition - turbulence (contributing factor)
  - weather condition - downdraft (contributing factor)
  - descent - not corrected
- In flight collision with terrain/water, descent

## Analysis

WHILE ON A X-COUNTRY FLT, THE ACFT ENCOUNTERED TURBULENCE & DOWNDRAFTS. THE PLT STATED THAT AT 1ST, HE WAS NOT CONCERNED, BUT THEN IT BECAME APPARENT THAT THE ACFT MAY IMPACT THE GROUND. THE ACFT HAD LIMITED POWER (75 HP) & THE TERRAIN ELEVATION IN THAT AREA WAS APRX 7000 FT MSL. SUBSEQUENTLY, THE ACFT DESCENDED INTO THE GROUND & FLIPPED OVER AFTER IMPACT.

## Aircraft

- Registration: [N37438](https://openairdocs.org/aircraft/N37438), registered now, S/N 283, built 1942 (OpenAirDocs)
- Reported make and model: INTERSTATE S-1A
- Registry model: [Interstate S-1A](https://openairdocs.org/model/interstate-s-1a) (registry code 1850202) (OpenAirDocs)
- Registry engine: [Continental A&C65 series](https://openairdocs.org/engine/continental-a-c65-series) (registry code 17003, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 283
- Engines: CONTINENTAL A-75 75 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Thomas H. Helton
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, February 16, 1985
- Departed: HARFORD, WY
- Destination: RKS, ROCK SPRINGS, WY

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 28; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; seat: front; flight hours: 553 total, 553 in this make and model, 553 as pilot in command, 91 in the last 90 days, 8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 220° at 20 knots, gusting 24
- Visibility: 80 statute miles
- Lowest ceiling: none
- Temperature: 84 °F
- Altimeter: 30.00 inHg
- Observed at: RKS, 41 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 19850801035389A](https://openairdocs.org/incident/19850801035389A), Aug 1, 1985: Arctic S1AARCTIC, Rock Springs, WY, Substantial damage. Aircraft with limited power encountered turbulence, descended into field and flipped over. High density altitude.

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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