What happened
On November 30, 2017, at 21:33 UTC, two aircraft were operating within the São Paulo Terminal Control Area (TMA-SP). The first aircraft, an EMB-505 with registration PP-LJA, was cruising at flight level 250 (FL250). The second aircraft, a B2/B200GT with registration PR-OTV, was climbing through FL245 toward a target altitude of FL270.
During the climb, the vertical separation between the two aircraft was reduced to only 300 feet. The crew of PP-LJA reported receiving a Traffic Collision Avoidance System (TCAS) Resolution Advisory (RA) indicating an aircraft 300 feet below them, while the crew of PR-OTV also received a TCAS RA indicating an aircraft above them. No damage was sustained by either aircraft, and all four crew members involved were uninjured.
The investigation
CENIPA's investigation focused on the air traffic control (ATC) sequence of events and the coordination between sectors. The investigation established that the controller in sector T8 had initially been informed by the previous sector (T7) that PR-OTV was restricted to FL200. However, the controller in T8, acting on his own initiative, released the restriction and authorized the aircraft to climb to FL270 without coordinating this change with the incoming sector's previous instructions.
Investigators found that the controller's attention was diverted toward the southern part of the sector because a supervisor was preoccupied with a separate conflict in the northern region. Furthermore, the controller's instructions to PR-OTV to stop its climb at FL240 were issued after the aircraft had already crossed FL245, and the subsequent vectors provided were not assertive enough to resolve the conflict before the separation became critical.
Findings
- Lack of coordination between sectors T7 and T8 regarding the altitude restriction for PR-OTV.
- Reduced situational awareness and attention of the T8 controller, influenced by high workload and external personal factors affecting the controller's routine.
- Inadequate traffic planning and failure to prioritize vertical separation between aircraft on the same route.
- Lack of assertiveness in ATC phraseology, which delayed the execution of necessary maneuvers to resolve the conflict.
- Inadequate decision-making by the controller, who failed to identify that the aircraft had already exceeded the requested altitude during the conflict resolution attempt.