Incident Overview
On August 1, 2011, at approximately 15:45 UTC, a loss of separation occurred between an ATR 42-500 registered F-GPYO, operated by Airlinair, and a private aircraft registered LX-FUN. The incident took place within the Chambéry Terminal Maneuvering Area (TMA), which is Class E airspace extending from 1,000 ft above surface to Flight Level 115.
Operational Context
The F-GPYO was on a scheduled passenger flight from Annecy to Paris Orly, climbing toward FL 110. The LX-FUN was on a private trip from La Mole to Luxembourg, cruising at FL 105. Both aircraft were operating under Visual Flight Rules (VFR) conditions, although the F-GPYO was an IFR flight.
Sequence of Events
At approximately 15:30 UTC, the LX-FUN pilot contacted the Chambéry Approach/Info controller regarding a direct route to Oyonnax. The controller advised that coordination with Geneva airspace was required but offered an alternative route allowing the aircraft to remain at FL 105.
Two minutes later, the F-GPYO crew contacted the same controller and received authorization to continue climbing to FL 110. The controller then provided traffic information to both crews, indicating their relative positions: the VFR aircraft was 7 nautical miles to the north of the IFR aircraft, 2,000 feet above it, and stable. Conversely, the IFR aircraft was reported as 7 nautical miles to the east of the VFR aircraft, 1,500 feet below, and climbing through its level.
Crew Actions and TCAS Usage
Upon receiving the traffic information, the F-GPYO crew stated they did not have visual contact but had a Traffic Collision Avoidance System (TCAS) advisory. Approximately one minute later, the crew announced they were turning 30 degrees to the right. The controller interpreted this as a visual avoidance maneuver.
However, the crew subsequently reported a second deviation of 30 degrees to the right, citing a TCAS alert. The controller suggested deviating to the left to cross the path of the LX-FUN, but the crew declined due to the TCAS display. The crew then announced they were climbing in response to a TCAS Resolution Advisory (RA) 'Climb'.
Separation and Conclusion
The minimum separation observed was 950 feet vertically and 1 nautical mile horizontally. The investigation concluded that the incident was caused by the F-GPYO crew's decision to use TCAS visual information for separation, a practice explicitly discouraged by Eurocontrol. Insufficient communication between the controller and the crew also contributed to the event, as they adopted different strategies for avoiding the conflict.