What happened
On April 6, 2015, at 15:32 local time, a near mid-air collision occurred in the approach area of Allgäu Airport Memmingen. An Airbus A320-232 was operating an IFR flight from Timisoara, Romania, to Memmingen, carrying 145 passengers and six crew members. Simultaneously, a Grob G102 glider was conducting a training flight in the vicinity of the Bad Wörishofen glider field under VFR conditions.
As the Airbus was descending through 4,300 ft AMSL following instructions from Munich Radar, the crew spotted the glider. The pilot monitoring immediately took control and initiated a manual climb to avoid the aircraft. Flight data from the Quick Access Recorder (QAR) confirmed that the autopilot was deactivated at 4,357 ft AMS/L, and the aircraft briefly descended to 4,329 ft before climbing back to 4,353 ft within a five-second window. No lateral avoidance maneuver was recorded.
The pilot of the Grob G102, a student pilot, reported seeing a light beam approaching while turning left. Upon recognizing the Airbus, the student pilot completed the turn and executed a descent and acceleration to increase separation. Radar data from the Bundeswehr measured the minimum distance between the two aircraft at 0.247 nautical miles.
The investigation
The BFU investigation examined radar data from both air traffic control and the Bundeswehr, as well as flight data from the Airbus QAR. The investigation also reviewed radio communications between the Airbus crew and Munich Radar and analyzed the flight profiles of both aircraft.
Findings
- The Grob G102 was flying without an active transponder, rendering it invisible to air traffic control radar.
- Because the glider lacked transponder information, the Airborne Collision Avoidance System (ACAS) installed on the Airbus A320-232 was unable to detect the glider.
- The encounter occurred in Class E airspace, where IFR and VFR traffic coexist, and the glider was not visible to controllers due to the lack of transponder signal.