What happened
On 23 July 2004, a near-miss incident occurred during the final approach to runway 05 at Geneva Airport. A LearJet 45, operating a commercial flight from Treviso to Geneva, was established on the ILS approach and descending through 6,000 ft. Simultaneously, a private Robin DR221 was conducting a VFR flight from Annecy to Dijon Darois.
The VFR pilot had previously contacted Chambéry Approach, where they were instructed to fly below 5,500 ft to avoid the Geneva TMA. However, the pilot selected transponder code A7061 without enabling Mode C, meaning their altitude was not visible to radar controllers. While navigating through the Geneva TMA, the Robin DR221 entered the Class C controlled airspace of Geneva TMA 1 without authorization.
As the LearJet 45 was intercepting the localizer, the Geneva Approach controller issued traffic information regarding an unknown aircraft crossing the path. The crew of the LearJet 45 reported seeing the traffic on TCAS and noted that the other aircraft had passed through the glide path altitude. To avoid a collision, the crew had to maintain their altitude of 6,000 ft. The minimum lateral separation between the two aircraft was recorded at 0.4 NM, with an estimated vertical separation of 500 ft.
The investigation
SUST examined radar recordings, radio communications, and pilot statements. The investigation established that the Robin DR221 entered the controlled Geneva TMA 1 airspace without clearance. The investigation also reviewed the transponder settings, finding that the pilot had failed to select Mode C, which prevented controllers from seeing the aircraft's altitude. Furthermore, the investigation looked into the coordination between Chambéry and Geneva ATC units regarding VFR traffic transit.
Findings
- The pilot of the Robin DR221 entered Class C controlled airspace without the required clearance.
- The pilot of the Robin DR221 used a transponder code that did not provide altitude information (no Mode C), making the aircraft a significant threat to IFR traffic.
- The LearJet 45 crew utilized TCAS to identify the traffic and successfully performed an avoidance maneuver by maintaining altitude.
- The investigation noted that VFR pilots often climb to avoid terrain, which can lead to unauthorized airspace incursions if they do not follow specific transit routes.
Safety action
- The investigation highlighted that appropriate coordination between Chambéry and Geneva ATC services is necessary to manage VFR traffic entering the Geneva TMA.
- It was noted that Chambéry Approach should avoid changing assigned transponder codes for VFR traffic before communication transfer to ensure continued identification and altitude monitoring.