Fatal MEDEVAC Crash in Manitoba Linked to Altitude Awareness and Fatigue

Casualties unknown • Thompson, Manitoba, CA

A Swearingen Merlin II crashed into a navigation tower near Thompson, Manitoba, resulting in two fatalities and one serious injury during a night medical evacuation flight.

What happened

On June 1, 1994, a Swearingen Merlin II was conducting a night medical evacuation flight from Churchill, Manitoba, to its base in Thompson. After completing a mission between Coral Harbour and Churchill, the crew began the return leg under instrument flight rules.

During the approach to Thompson Airport, the aircraft deviated from the published localizer back course procedure. While attempting to intercept the localizer, the aircraft descended below the required 1,500 feet altitude. The aircraft struck the Hotel non-directional beacon (NDB) tower and its guy wires, subsequently colliding with a second antenna tower before impacting the ground. The collision destroyed the aircraft and resulted in two fatalities among the crew and one serious injury to the flight nurse.

The investigation

The investigation focused on the crew's altitude awareness, the impact of weather, and the role of fatigue. Investigators examined the aircraft's radar altimeter, which was found to be functional and set to the minimum descent altitude. However, because the audio warning was not routed through the crew's headsets, the pilots may not have heard the descent alert.

Technical analysis of the wreckage showed no evidence of mechanical failure or flight control issues prior to the impact. The investigation also looked into the crew's workload, noting that the transition from air traffic control to flight service station communications, combined with the deviation from the standard approach, likely increased cockpit pressure.

Findings

  • The crew lost altitude awareness and allowed the aircraft to descend below the mandatory level-off altitude.
  • The flight crew deviated from the published approach procedure, which increased their workload and compressed the time available for monitoring the descent.
  • Rapidly developing localized fog placed the aircraft in instrument meteorological conditions, contrary to the crew's expectation of visual conditions.
  • The crew's monitoring of the approach was ineffective, potentially due to the pilot not properly setting navigational instruments.
  • Pilot fatigue was a significant contributing factor, as both pilots had been awake for approximately 17 hours and were experiencing the effects of disrupted sleep and high workload.

Probable cause

The primary cause of the accident was the flight crew's loss of altitude awareness, leading to a descent below the required minimum altitude. This was compounded by a deviation from the published approach, unexpected fog, and the physiological effects of fatigue.

Frequently asked questions

What happened in the 1994-06-01 Swearingen Merlin II C-FFYC accident near Thompson, Manitoba, CA?

A Swearingen Merlin II crashed into a navigation tower near Thompson, Manitoba, resulting in two fatalities and one serious injury during a night medical evacuation flight.

What aircraft was involved and where did it happen?

The accident on 1994-06-01 involved a Swearingen Merlin II C-FFYC, operated by Keewatin Air Limited, at Thompson, Manitoba, CA.

What was the probable cause of the accident?

The primary cause of the accident was the flight crew's loss of altitude awareness, leading to a descent below the required minimum altitude. This was compounded by a deviation from the published approach, unexpected fog, and the physiological effects of fatigue.

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