High-speed approach leads to structural failure of motor glider during out-landing

Casualties unknown • Accident with a motorglider west of Borås, SE

A motor glider experienced a broken fuselage after the pilot attempted an engine start during a low-altitude approach to an emergency landing field.

What happened

While participating in a regional gliding competition near Borås Airport, the pilot of an ASW 2/7-18E motor glider, registration SE-UJJ, encountered deteriorating weather conditions. As thermals weakened and cloud cover increased, the pilot identified an alternative landing field approximately 12 km from the airport.

As the aircraft approached the designated out-landing field, the pilot attempted to start the onboard engine. This process, which involves deploying the propeller and increasing airspeed to 120 km/h to facilitate a windmilling start, was initiated during the turn onto the base leg and continued through the final approach. The engine failed to ignite.

Due to the high speed required for the engine start attempt, the aircraft crossed the start of the field at 131 km/h and only 25 meters above the ground, significantly exceeding the flight manual's recommended approach speed of 100 km/h. The aircraft touched down 177 meters into the 340-meter-long field at 123 km/h. Realizing the remaining runway was insufficient to stop before an embankment, the pilot executed an intentional ground loop to decelerate. The force of the maneuver caused the aft fuselage to break.

The investigation

SHK analyzed GPS data and interviewed the pilot to reconstruct the flight path. The investigation focused on the sequence of maneuvers leading to the high-speed touchdown. Investigators noted that the engine start attempt occurred at a low altitude, which constrained the pilot's options for managing the landing.

Findings

  • The late attempt to start the engine was the primary cause of the accident, as it necessitated an airspeed much higher than recommended for a safe approach.
  • The pilot's attention was divided between monitoring the engine start and managing the landing parameters, reducing the capacity for effective landing assessment.
  • The engine on this aircraft type is not intended to be relied upon as a primary safety mechanism for avoiding out-landings.
  • The pilot had pre-selected the landing field before attempting the start, indicating an awareness of the potential for engine failure.

Probable cause

The accident was caused by the pilot's decision to attempt an engine start at a low altitude during the final stages of the approach, which resulted in an approach speed significantly higher than the recommended limit and left insufficient distance to stop safely.

Frequently asked questions

What happened in the 2017-07-11 aircraft accident near Accident with a motorglider west of Borås, SE?

A motor glider experienced a broken fuselage after the pilot attempted an engine start during a low-altitude approach to an emergency landing field.

What aircraft was involved and where did it happen?

The accident on 2017-07-11 involved a aircraft, at Accident with a motorglider west of Borås, SE.

What was the probable cause of the accident?

The accident was caused by the pilot's decision to attempt an engine start at a low altitude during the final stages of the approach, which resulted in an approach speed significantly higher than the recommended limit and left insufficient distance to stop safely.

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