What happened
On June 17, 2019, an AS 350B3 helicopter, registration HB-ZSL, was performing a VFR approach to Geneva Airport (LSGG) for a landing at the northern helipad. During the approach, the helicopter pilot was in contact with Geneva Tower, with instructions being delivered in French. Simultaneously, a Cessna Citation 510, registration OE-FCB, was cleared for takeoff from intersection Z on runway 04. The crew of the Citation was communicating with ATC in English.
As the helicopter descended, the controller asked the helicopter pilot if they had the Citation in sight. The helicopter pilot observed a small jet moving on taxiway Y and confirmed visual contact. However, the aircraft the pilot actually saw was a Phenom 300 that was vacating the runway via taxiway Y, not the Citation preparing for takeoff. Based on this visual confirmation, the controller cleared the helicopter to cross the runway axes and land behind the traffic on taxiway Y.
This resulted in the HB-ZSL crossing the runway centerline directly in front of the departing OE-FCB. The horizontal separation between the two aircraft reduced to approximately 80 meters, while the vertical separation was roughly 400 feet. The crew of the Citation 510 noticed the helicopter and reacted by reducing their rate of climb to pass beneath the conflicting aircraft.
The investigation
The investigation by SUST examined ATC recordings, ground movement surveillance (SAMAX 4), and pilot statements. The inquiry focused on the communication between the tower and the helicopter pilot, as well as the visual identification of aircraft on the ground.
Findings
- The primary cause of the incident was the pilot's confusion between the departing aircraft and the taxiing aircraft.
- The controller's instruction regarding the Citation was ambiguous, as it did not specify whether the aircraft was at intersection Y or Z.
- The helicopter pilot misidentified the Phenom 300 on taxiway Y as the Citation because the aircraft's silhouette was similar from the pilot's perspective.
- The pilot in the right seat of the helicopter was in a blind spot regarding the actual takeoff at intersection Z.
- The Citation crew did not understand the French-language instructions directed at the helicopter, which prevented them from realizing the helicopter intended to cross behind them.
- High traffic density at the time of the incident contributed to the complexity of the situation.