History of the Flight
On 27 June 2016 at 15:43 UTC, the crew of Air France flight HOP25PG, an Airbus A319 registered F-GRHX, contacted Marseille-Provence approach while descending from Bordeaux. They reported the airfield in sight and requested a visual approach to runway 31R. At 15:48, an AS532 Cougar helicopter registered F-ZWBS, call sign Cougar India, returning from a VFR checkout flight, contacted Provence info. The helicopter's transponder had failed, so air traffic control had only primary radar contact. The Cougar was instructed to descend to 1,500 ft and later to contact the tower controller.
Due to frequency congestion, the Cougar established contact with the tower at 15:50:33. The tower controller noted only a primary blip and directed the crew to join a right-hand base leg for runway 31, positioning behind an A320. The Cougar crew reported visual contact and read back instructions. At 15:51:40, the approach controller cleared the A319 to descend to 5,000 ft and informed them they were number two behind the same Lufthansa flight.
Conflict Development
While on base leg, the Cougar crew initiated a hover flight without informing the controller. Radar contact with the helicopter was consequently lost. The Cougar then proceeded toward the MS point. Neither crew was aware of the other's proximity. The two aircraft crossed paths, and visual contact was made only after the closest approach. Recorded minimum separation was 0.19 NM horizontally and 240 ft vertically.
Investigation Findings
The French safety investigation authority (BEA) determined that the near collision resulted from a combination of factors. No segregation measures were taken for the Cougar, which operated without a transponder in dense traffic where compatibility of IFR and VFR flights relies on traffic information and visual contact. The Cougar crew did not comply with the aerodrome circuit altitude and failed to advise of the hover. Their position reports were inaccurate, leading the controller to form an erroneous mental picture and provide unsuitable traffic information. Controllers were also not informed about areas where primary radar returns were not displayed.
Contributing factors included the absence of an overall sequencing strategy for inbound VFR and IFR traffic, controller workload limiting anticipation, excessive flexibility in parallel runway management, congested tower frequency with non-standard phraseology delaying the A319's contact, and possible overconfidence due to the Cougar crew being local professionals.
Safety Recommendations
The BEA issued five safety recommendations to the French air navigation service provider (DSNA) concerning spatial and temporal segregation of flights with failed transponders, provision of information on radar performance limitations, assessment of extending these measures, implementation of shared traffic sequencing strategies at Marseille-Provence, and analysis of work methods for safe traffic sequencing on one of the parallel runways.