Serious incident to the Socata TB20 registered F-GGNS and to the Beech G58 registered F-GNSD on 06/10/2021 at Saint-Yan

On the day of the incident, the work period was ending. In the morning, the runways were closed alternately and some work was still being carried out on some taxiways. The tower controller started her shift in the morning and, due to the low traffic levels, managed the GND and LOC functions (combined positions). In the early afternoon, with both runways back in use, air traffic increased. During the take-off of a TB 20 in IFR flight and the touch-and-go of a Be 58 a few seconds later, the controller had considered asking the Be 58 to turn onto the left-hand downwind leg after its initial climb. The presence of an external VFR flight, a DR 400 wanting to perform an airport circuit for training and at that moment heading towards the downwind leg, altered her initial strategy. She then asked the pilot of the Be 58 to continue his initial climb. Her idea was then to ask him to turn onto the downwind leg as soon as the position of the DR 400 would allow it.

The controller was then surprised by the closing speed between the Be 58 and the TB 20. She reported that she detected the conflict but that, due to a resource-intensive traffic sequence, no longer had sufficient mental resources to manage the conflict in the time available. Only the pilot of the Be 58 was informed of the presence of the TB 20 to his front right, about 25 s before overtaking it and before the planned turn to the left of the latter. He acquired visual contact with the TB 20 when overtaking it, but did not announce it.

The TB 20 pilot had monitored the traffic on the frequency and perceived the conflicting presence of the Be 58 to his rear left. He anticipated the closing-in and did not make the left turn of his IFR omnidirectional departure, and was then instructed by the controller to hold the runway axis, thereby eliminating the risk of collision.