Incident Overview
On 25 August 2016 at 15:36 UTC, a serious incident (Airprox) occurred approximately 13 nautical miles northwest of Zurich Airport. The involved aircraft were an Airbus A330-343, registered as HB-JHR and operated by Edelweiss Air under flight plan designation EDW3A, and a Scheibe Flugzeugbau SF25 motor glider, registered as D-KOWC, operated by Luftsportverein Greiz e.V.
Sequence of Events
The Airbus A330 was flying under Instrument Flight Rules (IFR) on a scheduled flight from Las Vegas (KLAS) to Zurich (LSZH). The motor glider was operating under Visual Flight Rules (VFR) on a private flight from Bremgarten (EDTG) to Biberach (EDMB). At the time of the incident, the A330 was in contact with Approach West (APW) of Zurich approach control and was being radar vectored for an approach to runway 14. The motor glider had no communication with air traffic control and its transponder was switched off. The closest proximity between the two aircraft was approximately 300 meters horizontally and 0 feet vertically. The prescribed minimum separation in Class C airspace is 3 nautical miles horizontally or 1000 feet vertically.
Aircraft and Crew Information
The Airbus A330 was owned by Swiss International Air Lines Ltd. and operated by Edelweiss Air AG. The motor glider was owned and operated by Luftsportverein Greiz e.V. The investigation did not specify details about the crews' qualifications or experience beyond stating that the motor glider pilot had low flight experience, which was identified as a contributing factor.
Causes
According to the Swiss Transportation Safety Investigation Board (STSB), the serious incident was caused by a navigation error by the motor glider pilot, who entered an approach sector of Zurich Airport without communication means and with the transponder switched off. This prevented the generation of safety warnings related to the situation. The pilot's low flight experience was a contributing factor.
Findings
The STSB's investigation concluded that the motor glider pilot navigated into controlled airspace without proper communication and with the transponder off. The airliner's crew and air traffic control were unaware of the conflicting traffic until the close encounter occurred. No injuries or damage to either aircraft were reported in the source.