# NTSB CHI91DEP03: Air Command 503, Tomahawk, WI, January 15, 1991

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Final report
- Date: January 15, 1991, 15:10 local (21:10 UTC)
- Place: Tomahawk, WI
- Coordinates: 45.470035, -89.719459 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.4700&lon=-89.7195&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report December 4, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14836
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI91DEP03
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14836/pdf
- Page: https://openairdocs.org/ntsb/CHI91DEP03

## Probable cause

THE PILOT-IN-COMMAND'S ABRUPT MOVEMENT OF THE FLIGHT CONTROLS WHICH RESULTED IN LOSS OF ROTOR RPM AND EVENTUAL DEPARTURE FROM CONTROLLED FLIGHT. A FACTOR CONTRIBUTING WAS ICE ACCUMULATION ON THE PILOT'S FACE RESULTING IN PILOT INCAPACITATION (VISUAL DEFICIENTY).

## Sequence of events

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

- Abrupt maneuver, approach - vfr pattern - downwind
  - rotorcraft flight controls - abrupt, pilot in command (cause)
  - rotor rpm - not maintained, pilot in command
  - weather condition - icing conditions
  - incapacitation(visual deficiency), pilot in command (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE PILOT OF AN UNREGISTERED GYRO-COPTER WAS MAKING TAKEOFFS AND LANDINGS IN CONDITIONS CONDUCIVE TO ICING. HE MADE A LANDING AND COMPLAINED OF ICE ON HIS GLASSES TO A WITNESS. WHEN NO GOGGLES COULD BE LOCATED HE STATED THAT HE WOULD MAKE ONE MORE TAKEOFF AND LANDING. ON THE DOWNWIND LEG OF THE FLIGHT THE AIRCRAFT WAS OBSERVED BY WITNESSES TO DEPART CONTROLLED FLIGHT, TUMBLE, AND IMPACT THE TERRAIN. WITNESSES STATED THAT DURING AN ATTEMPT TO REVIVE THE PILOT HE HAD AN ACCUMULATION OF ONE QUARTER INCH OF ICE OVER HIS EYES AND FACE.

## Aircraft

- Registration: UNREG (not matched to a registry record)
- Reported make and model: AIR COMMAND 503
- Category: Gyroplane, amateur-built
- Engines: ROTAX 503 47 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Charles R. May
- Airport: WI46, Tomahawk Regional, runway 27, 4,000 × 25 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; flight hours: 12 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 45° at 2 knots
- Visibility: 7 statute miles
- Lowest ceiling: 1,000 ft overcast
- Temperature: 25 °F, dew point -0 °F
- Altimeter: 29.00 inHg

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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