What happened
On September 11, 2022, a Rolladen-Schneider LS4-b glider, registered PH-1274, was performing a local flight departing from Teuge International Airport. While flying north of Apeldoorn at approximately 1,200 feet, the pilot observed a second aircraft approaching directly from the right. To avoid a collision, the glider pilot executed a descending left turn.
Simultaneously, a Cessna 208B, registered PH-SPT, was conducting a parachute jump operation. The aircraft was climbing in a northerly direction at approximately 2,000 feet. Due to the aircraft's high pitch attitude during a right-hand turn, the pilot's forward visibility was significantly restricted. The pilot only noticed the glider after the glider pilot had already initiated an evasive maneuver. In response, the Cessna pilot increased the angle of attack to a maximum climb, which triggered the aircraft's stall warning. Radar data indicates the two aircraft passed each other with a vertical separation of only about 100 feet and a horizontal separation of roughly 40 metres.
The investigation
The Dutch Safety Board examined radar imagery and pilot statements to reconstruct the flight paths. The investigation focused on the visibility constraints of the Cessna 208B and the effectiveness of collision avoidance technology. The investigation confirmed that the aircraft were operating in G class airspace, where pilots are personally responsible for maintaining separation.
Findings
- The primary cause of the near-miss was the high pitch attitude of the Cessna 208B, which prevented the pilot from seeing the approaching glider.
- The Cessna 208B was not yet equipped with the FLARM collision avoidance system, which would have provided an automated warning.
- The glider, PH-1274, was equipped with FLARM, but the system did not issue a warning because the other aircraft lacked the necessary transponder technology.
- The collision was avoided only because the glider pilot recognized the danger and performed an immediate descending turn.