Introduction
On 25 October 2010, a serious incident classified as an airprox occurred involving two commercial aircraft near the DVOR Trasadingen waypoint in Switzerland. The aircraft involved were an Airbus A320-232, registered as CS-TQK and operating under call sign CFG 366, and an Airbus A340-642 operating under call sign QTR 020. CFG 366 was a charter flight on behalf of Condor Flugdienst GmbH, operated by White Airways S.A. of Portugal. QTR 020 was operated by an unspecified airline. The incident took place approximately 3 nautical miles north-east of the DVOR Trasadingen (TRA) navigation aid.
Aircraft and Crew Information
The A320-232 was manufactured by Airbus S.A.S. and its owner was Wells Fargo Bank Northwest, National Association, USA. Both aircraft were operating under Instrument Flight Rules (IFR). The flight crews held valid licenses and were within duty time limits. The commander of CFG 366 had extensive flying experience, as did the copilot. The crew of QTR 020 also met all regulatory requirements.
Incident Sequence
According to the investigation, the serious incident unfolded when the crew of QTR 020 deviated from its air traffic control (ATC) clearance. During the approach, the crew of QTR 020 initiated a standard VOR letdown procedure but did not adhere to the prescribed Flight Crew Operating Manual (FCOM) procedure. The deviation brought the aircraft into close proximity with CFG 366. The Traffic Collision Avoidance System (TCAS) on both aircraft generated a Resolution Advisory (RA). The crew of CFG 366 complied with the RA, but the crew of QTR 020 did not follow the TCAS RA as required.
Cause
The Swiss Accident Investigation Board (SAIB) determined that the serious incident was attributable to the crew of QTR 020 deviating from its ATC clearance and not following the TCAS Resolution Advisory. A contributing factor was that the crew of QTR 020 did not comply with the requirements of the FCOM procedure when carrying out a standard VOR letdown procedure.