Incident Overview
On June 1, 2015, at approximately 16:27 local time, a serious incident occurred near Bergheim involving a Cessna 172R and an unidentified glider. The event was classified as a severe disturbance by the German Federal Aviation Accident Investigation Office (BFU). No personal injuries or material damage were reported.
Flight Details and Sequence of Events
The Cessna 172R, operated by a German flight school, was conducting an Instrument Flight Rules (IFR) training flight from Cologne-Bonn to Mönchengladbach. The aircraft carried a flight instructor and a student pilot. At the time of the incident, the Cessna was descending through instrument meteorological conditions.
The student pilot, who was monitoring the navigation equipment, first noticed movement out of the corner of his eye. He identified a glider approaching from the left, slightly below the Cessna's altitude. The flight instructor confirmed the sighting, noting red adhesive strips on the glider's nose and wingtips. Both aircraft were on a collision course due to the Cessna's descent and the glider's trajectory.
Avoidance Maneuver
Upon identifying the conflict, the flight instructor immediately aborted the descent. He initiated a climb and executed a right turn. The maneuver brought the Cessna to approximately 4,200 feet AMSL before leveling off in horizontal flight once the student confirmed the glider was no longer a threat. The Cessna subsequently landed safely at Mönchengladbach.
Investigation Findings
The glider involved could not be identified. It did not have an active transponder and therefore did not appear on the air traffic control radar displays, which rely on transponder signals for continuous tracking with altitude data. Primary radar data from the Bundeswehr recorded a target 0.4 nautical miles southeast of the Cessna moving northeast, but this was insufficient to determine the glider's origin or destination.
The investigation highlighted that in Class E airspace, IFR flights are separated from other IFR flights but not necessarily from VFR traffic like gliders. Traffic information is provided where possible, but reliable collision avoidance systems and ATC services depend on transponder emissions.