What happened
On June 17, 2004, a Kolb Twinstar Mark III micro light aircraft, registration PH-2T4, attempted to depart from a field near Oudehorne for an overland flight to Volkel. The flight was intended to be a group departure with another aircraft. The takeoff was conducted from a grassy field measuring approximately 550 meters in length.
During the takeoff roll, the pilot noted that the aircraft required significantly more distance than the usual 150 meters, likely due to the relatively long grass. As the aircraft gained speed, it began to veer left toward the wind. The pilot reported that the controls felt unusually light, and the aircraft struggled to climb. While attempting to pass a nearby farm on the right side, the aircraft lost altitude at approximately 10 meters, struck the ground on the left side of the farm, and was destroyed. Both occupants sustained injuries, with one being serious.
The investigation
The investigation examined the aircraft's weight, the environmental conditions, and the takeoff procedures. Although the aircraft and engine were nearly new, with only nine total flight hours, several critical factors were identified.
Wind conditions at the time included gusts of up to 29 knots, with a crosswind component of approximately 12 knots. While this was within the maximum allowable limit for the type, the presence of a tree line nearby likely introduced turbulence. Furthermore, the investigation found that the aircraft was likely overweight, with an estimated total weight of 412 kg, exceeding the maximum takeoff weight of 390 kg by approximately 22 kg.
Additionally, the investigation noted that the pilot did not utilize flaps during the takeoff, despite the flight manual for an identical aircraft recommending a 15-degree setting. The investigation also found that the takeoff was being conducted from a field that was not a certified aerodrome and lacked the necessary legal exemptions.