Fatal Stall During Engine Failure Drill in Cessna 150

Casualties unknown • Turweston Aerodrome, Northamptonshire, GB

A training flight at Turweston Aerodrome resulted in a fatal accident when a Reims Cessna 150 entered a spin during a simulated engine failure.

What happened

On 4 February 1999, a Reims Cessna 150L, registration G-AZLL, was conducting a training flight at Turweston Aerodrome. The flight, intended to introduce a student to circuits, had previously completed several laps before the crew paused for a break. Upon resuming the flight, the instructor intended to demonstrate an Engine Failure After Take Off (EFATO) procedure.

During the climb, the instructor partially closed the throttle to simulate a power loss. Witnesses observed the aircraft flying at a very low speed and height, appearing to wobble before the left wing dropped suddenly. The aircraft then entered a rapid nose-down spiral, impacting the ground near the end of Runway 27. The impact destroyed the aircraft. The instructor sustained one fatal injury, while the student sustained one serious injury.

The investigation

The investigation focused on the aircraft's configuration and the environmental conditions. At the time of the accident, the area was experiencing strong winds, with gusts up to 30 knots and a forecast for severe turbulence.

Investigators examined the flap mechanism and found the flaps were extended to the 40° position. This high-drag setting requires a specific nose attitude and high power to maintain airspeed. While the cause of the flap deployment could not be definitively established, a wire connected to the down limit microswitch was found disconnected. This wire was part of a loose bundle and was prone to disconnection due to a damaged end fitting.

Regarding occupant safety, the student was wearing a full four-point harness, but the instructor was only using the lap strap portion of his harness. The investigation noted that the instructor's lack of upper torso restraint likely contributed to the severity of his injuries when he was thrown forward during the impact.

Findings

  • The aircraft was operating in high-drag configuration with 40° of flap selected.
  • The combination of high drag, low power, and gusty, turbulent conditions likely led to a sudden and critical loss of airspeed.
  • The aircraft experienced a stall and a subsequent wing drop, leading into an incipient spin.
  • The instructor's use of only the lap strap portion of the harness likely contributed to the fatal nature of his injuries.

Probable cause

The accident was caused by a sudden loss of airspeed leading to a stall and spin, likely precipitated by the high-drag 40° flap setting and turbulent wind conditions during a simulated engine failure maneuver.

Frequently asked questions

What happened in the 1999-02-04 REIMS CESSNA FRA150L accident near Turweston Aerodrome, Northamptonshire, GB?

A training flight at Turweston Aerodrome resulted in a fatal accident when a Reims Cessna 150 entered a spin during a simulated engine failure.

What aircraft was involved and where did it happen?

The accident on 1999-02-04 involved a REIMS CESSNA FRA150L, registration G-AZLL, at Turweston Aerodrome, Northamptonshire, GB.

What was the probable cause of the accident?

The accident was caused by a sudden loss of airspeed leading to a stall and spin, likely precipitated by the high-drag 40° flap setting and turbulent wind conditions during a simulated engine failure maneuver.

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