What happened
On 23 November 2025, two commercial Embraer flights experienced a serious loss of separation while operating near the UTREX Waypoint. The first aircraft, an Embraer EMB-ERJ-135MP registered ZS-TCE, was performing a scheduled flight from O.R. Tambo International Airport to Skukuza Airport. Simultaneously, an Embraer EMB-E190-100IGW registered ZS-YAM was departing Skukuza for O.R. Tambo.
As the aircraft approached the same waypoint from opposite directions, the flight crew of ZS-YAM noted the presence of the inbound ZS-TCE on the shared radio frequency. To increase safety margins, the ZS-YAM crew initiated a rapid climb. During this period, the Traffic Collision Avoidance System (TCAS) on both aircraft activated. The ZS-YAMD crew received a "DESCEND" resolution advisory, while the ZS-TCE crew received a "CLIMB" advisory. Both flight crews executed the commanded maneuvers immediately, successfully resolving the conflict. No injuries or aircraft damage were reported.
The investigation
SACAA AIID examined the flight communications and air traffic control (ATC) recordings from the Lowveld Airspace Control Sector. The investigation focused on the altitude clearances provided to both aircraft and the accuracy of the flight crew's readbacks. Investigators also reviewed the maintenance records and pilot licenses for both the ZS-TCE and ZS-YAM operations, confirming that both crews were properly licensed and the aircraft were airworthy.
Findings
- The primary cause of the incident was inadequate vertical separation between the two aircraft as they converged on the UTREX Waypoint.
- A critical error occurred when the ZS-TCE crew provided a clearance readback that contained conflicting altitude and reporting instructions, which was not corrected by ATC.
- The ZS-TCE aircraft descended past its assigned reporting level without notifying the controller.
- Increased airspace complexity and controller workload contributed to the breakdown in communication.
- The incident was exacerbated by a reliance on pilot self-separation awareness rather than active ATC intervention.
Safety action
- It is recommended that the Air Navigation Service Provider review arrival and departure procedures for Skukuza Airport, specifically regarding the UTREX Waypoint, to ensure vertical separation is maintained.
- The Lowveld Airspace Control Sector should review controller workload to reduce task saturation.
- Operators should continue to emphasize crew awareness of routing constraints and the importance of responding to TCAS alerts.