In-flight collision with terrain during instrument approach

No fatalities • Miles City, United States of America • Landing (descent or approach)

An aircraft crashed into mountainous terrain during an instrument approach due to an incorrect altimeter setting and failure to maintain minimum altitudes.

What happened

During an instrument approach in low visibility, the pilot requested a new altimeter setting via radio. The received information was approximately 30.11 or 30.12 inches of mercury; however, the aircraft's altimeter was later found to be set at 30.22 inches of mercury. At the time of the flight, visibility was limited to 1.5 miles due to snow showers.

As the pilot proceeded with the approach, the aircraft descended outbound to 4,500 feet, which was below the required minimum procedure turn altitude of 4,700 feet MSL. Upon approaching the VOR, the aircraft continued to descend to 3,700 feet MSL. During this phase, manifold pressure was reduced to approximately 17-18 inches and airspeed was lowered to 120 knots. The landing gear and approach flaps were deployed.

While crossing the VOR, the pilot checked the altimeter and observed the hands at the two o'clock position. Shortly after, while observing clouds through the window, the aircraft struck the terrain. The pilot survived the impact and managed to exit the cockpit via the window, wandering for several hours before being located.

Findings

The investigation identified several contributing and factual factors regarding the crash:

  • The primary cause was an incorrect altimeter setting used by the pilot in command.
  • The aircraft failed to maintain the required minimum descent altitude.
  • The flight occurred in mountainous terrain during dark night conditions.
  • Weather conditions included low ceilings and obscuration caused by snow showers.
  • Improper IFR procedures were followed by the pilot.

Probable cause

The accident was caused by the pilot's use of an incorrect altimeter setting and failure to maintain prescribed minimum altitudes during the approach.

Frequently asked questions

What happened in the 1984-03-31 Rockwell Aero Commander 500 accident near Miles City, United States of America?

An aircraft crashed into mountainous terrain during an instrument approach due to an incorrect altimeter setting and failure to maintain minimum altitudes.

Were there any fatalities in the 1984-03-31 Rockwell Aero Commander 500 accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 1984-03-31 involved a Rockwell Aero Commander 500, registration N743W, operated by Combs FreightAir, at Miles City, United States of America.

What was the probable cause of the accident?

The accident was caused by the pilot's use of an incorrect altimeter setting and failure to maintain prescribed minimum altitudes during the approach.

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