What happened
On October 13, 2020, at 17:48 UTC, an Airbus A320-214, registration PR-MYW, operated by TAM Linhas Aélaras S.A., was descending toward Marechal Rondon Aerodrome (SBCY) in Cuiabá, Mato Grosso. Simultaneously, a Piper PA-31T1, registration PT-OLF, was cruising on an opposite heading after departing from the same airport.
As the aircraft approached the boundary between Cuiabá Approach Control (APP-CY) and the Amazon Area Control Center (ACC-AZ), the separation between the two aircraft dropped below regulatory minimums. At the moment of closest approach, the aircraft were separated by only 100 feet vertically and 0.2 nautical miles horizontally. The crew of the A320-214 performed an evasive maneuver following a Resolution Advisory (RA) from the Traffic Collision Avoidance System (TCAS). There were no injuries to the 162 occupants on the Airbus or the 4 occupants on the Piper, and no damage was sustained by either aircraft.
The investigation
CENIPA's investigation focused on the coordination between the two air traffic control units and the adherence to established operational agreements. Investigators examined the transfer of aircraft control between APP-CY and ACC-SB, the use of the SAGITÁRIO air-to-air conflict alert system, and the communication logs between controllers. The investigation also reviewed the training and experience levels of the air traffic controllers on duty, specifically noting the impact of early aircraft transfers that deviated from the established Letter of Agreement (CAOp).
Findings
- Loss of separation was driven by a failure to follow established procedures for transferring aircraft between control sectors.
- Air traffic controllers demonstrated inadequate coordination and excessive informality during the exchange of information between units.
- The controller at APP-CY experienced a loss of situational awareness, characterized by "tunnel vision," as focus was diverted to other traffic.
- The SAGITÁRIO system's air-to-air conflict alert was not properly utilized by the ACC-AZ team.
- Controllers failed to apply the parameters of the Letter of Agreement, transferring aircraft between sectors earlier than prescribed, which led to a lack of clear responsibility for the conflicting traffic.
- There was a lack of effective supervisory intervention to monitor and correct the operational deviations.