What happened
On May 8, 2004, a Grob G 115 was conducting a training flight at Seppe airfield. Following a standard circuit and landing, the instructor and student decided to practice a simulated engine failure by performing a glide approach to runway 07. During this maneuver, the engine power was reduced to idle at the upwind leg, and the aircraft transitioned through the crosswind leg to the final approach.
The instructor reported that the aircraft's speed was 65 knots with flaps set to the second position when the aircraft began to sink unexpectedly. In an attempt to recover, the instructor applied full power and pitched the nose up into a slight climb. Despite these corrective actions, the aircraft struck barbed wire fencing located before the runway threshold. The aircraft subsequently landed on the grass area preceding the paved runway. Upon taxiing to the parking area, significant damage was discovered: the right elevator had been torn from the stabilizer after catching on the wire, and a hole was found in the right wing caused by a fence post.
The investigation
The investigation, conducted by the predecessor to the Dutch Safety Board, relied on data provided by the instructor and findings from the aviation police report. Investigators analyzed the mechanics of a glide approach, noting that a successful maneuver should result in a touchdown at the one-third mark of the runway to provide a safety margin.
At Seppe, the distance from the perimeter fence to the one-in-third point of runway 07 is approximately 350 meters. The investigation considered two primary possibilities for the undershoot: that the initial glide path was calculated too shallow, or that the aircraft encountered wind shear. The investigation noted that the approach to runway 07 involves flying over a viaduct with nearby vegetation; the instructor noted that recent growth in this area might now trigger wind shear under specific wind conditions. Notably, a similar incident involving a different aircraft occurred at the same airfield under nearly identical weather conditions in September 2004.
Safety action
Following the incident, the flight school implemented several procedural changes for its instructors, students, and renters, including:
- Revised landing procedures regarding airspeed and technique.
- A prohibition on solo student flights during weather conditions identical to the accident.
- A prohibition on practicing glide approaches during such weather conditions.