# NTSB DEN84FA121: Aero Commander 500-B, N743W, Miles City, MT, March 31, 1984

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: March 31, 1984, 02:03 local (09:03 UTC)
- Place: Miles City, MT
- Coordinates: 46.220188, -105.5997 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.2202&lon=-105.5997&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16207
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84FA121
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16207/pdf
- Page: https://openairdocs.org/ntsb/DEN84FA121

## Sequence of events

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

- In flight collision with terrain/water, approach - faf/outer marker to threshold (ifr)
  - terrain condition - mountainous/hilly (contributing factor)
  - altimeter setting - improper, pilot in command (cause)
  - weather condition - low ceiling (contributing factor)
  - ifr procedure - improper, pilot in command (cause)
  - weather condition - obscuration (contributing factor)
  - proper altitude - below, pilot in command (cause)
  - light condition - dark night (contributing factor)
  - minimum descent altitude - not maintained, pilot in command (cause)

## Analysis

THE PLT SAID THAT WHEN HE CALLED ON THE RADIO PRIOR TO THE APPROACH FOR AN ALTIMETER SETTING THE REPLY WAS '30.11 OR 30.12, SOMETHING LIKE THAT.' THE ACFT ALTIMETER WAS FOUND AFTER THE ACCIDENT SET AT 30.22 INCHES OF MERCURY. THE VISIBILITY WAS DESCRIBED AS 1 AND 1/2 MILES IN SNOW SHOWERS. HE CONTINUED THE APPROACH 'BECAUSE MINIMUMS ARE ONE MILE.' HE DESCENDED OUTBOUND TO 4500 FT. MINIMUM PROCEDURE TURN ALT IS 4700 FT MSL. THE PLT THEN DESCENDED TO 3700 FT MSL AS HEAPPROACHED THE VOR. POWER WAS REDUCED TO 17-18 INCHES OF MANIFOLD PRESSURE AND AIRSPEED REDUCED TO 120 KTS. AS THE VOR WAS CROSSED HE GLANCED AT THE ALTIMETER AND 'THE HANDS WERE IN THE TWO O'CLOCK POSITION.' LANDING GEAR WAS EXTENDED AND APPROACH FLAPS SET. THE PLT SAID ALL SEEMED NORMAL. HE LOOKED OUT THE WINDOW AND SAW 'WISPY CLOUDS GOING BY RAPIDLY. THEN THERE WERE THE SOUNDS OF IMPACT.' THE NEXT THING REMEMBERED WAS THE SOUND OF DRIPPING GASOLINE. THE PLT SAID HE CRAWLED OUT OF THE COCKPIT WINDOW AND WANDERED 'FOR A COUPLE HOURS TRYING TO CHASE DOWN THE SEARCH LIGHTS.'

## Aircraft

- Registration: [N743W](https://openairdocs.org/deregistered/N743W-2012-10-19), registration cancelled 2012-10-19, S/N 500B-1173-89, built 1962 (OpenAirDocs)
- Reported make and model: AERO COMMANDER 500-B
- Registry model: [Aero Commander 500-B](https://openairdocs.org/model/aero-commander-500-b) (registry code 0141106) (OpenAirDocs)
- Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Serial number: 500B117389
- Airframe hours: 13453
- Engines: LYCOMING IO-540-B1A5 290 horsepower reciprocating
- Damage: Destroyed
- Flight: Part 135
- Registered owner: Combs Airways, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, March 23, 1984, 12 hours before
- Departed: BIL, BILLINGS, MT
- Flight plan: IFR
- Airport: MLS, Frank Wiley, runway 12, 5,602 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 2,750 total, 394 in this make and model, 2,131 as pilot in command, 199 in the last 90 days, 66 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Instrument (IMC), Night/dark
- Wind: 100° at 12 knots
- Lowest ceiling: 1,500 ft
- Temperature: 32 °F, dew point 27 °F
- Altimeter: 30.00 inHg
- Observed at: MLS, 2 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 19840331065249A](https://openairdocs.org/incident/19840331065249A), Mar 31, 1984: Gulstm 500B, Miles City, MT, Destroyed. Flew into the ground during a VOR approach in a heavy snow shower. Failed to adhere to minimum descent 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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