What happened
On the afternoon of 20 August 2024, a training flight involving a flight instructor and a student pilot in a Robinson R44 II, registration ZT-RFJ, was performing a circuit at Grand Central Aerodrome (FAGC) in Gauteng. Simultaneously, a Sling 4, registration ZU-EX, was conducting a test flight with a pilot and an engineer.
After taking off from Runway 35, the pilot of the Sling 4 requested and received permission from Air Traffic Control (ATC) to execute an early left turn. While the controller had notified the Sling 4 crew of the presence of the ZT-RFJ helicopter, the helicopter crew was not alerted to the fixed-wing aircraft's new flight path. Shortly after, the helicopter crew experienced a TCAS alert and observed the Sling 4 crossing directly in front of them. To prevent a collision, the helicopter pilot was forced to descend to a lower altitude. There were no injuries and no damage to either aircraft.
The investigation
SACAA AIID examined the communications between the air traffic control officer (ATCO) and both aircraft. The investigation established that while the Sling 4 pilot initially reported having the helicopter in sight, the pilot subsequently lost visual contact with the ZT-RFJ. The investigation also reviewed the ATCO's actions, noting that the controller provided traffic information to the departing aircraft but failed to relay the change in traffic pattern to the aircraft already established in the circuit.
Findings
- The ATCO authorized an early left turn for the Sling 4 while the ZT-RFJ was active in the left circuit for Runway 35.
- The ATCO failed to warn the helicopter pilot of the proximity of the Sling 4 or the pilot's intention to turn early.
- The Sling 4 pilot lost sight of the ZT-RFJ during the maneuver.
- The intersection of the two flight paths resulted in reduced aerodrome separation and a significant risk of collision.
Safety action
- Air Traffic Control Officers are advised to avoid authorizing early turns when managing mixed or conflicting traffic and must ensure that all affected aircraft are provided with updated traffic information.