What happened
On January 18, 2025, at 20:55 UTC, a Boeing 737-800, registration LV-KCE, operating as flight FBZ 5062, departed El Palomar Airport (SADP) following the PALOMAR 9 standard instrument departure. During the climb, the aircraft was transferred to the Buenos Aires Terminal Control Area (TMA BAIRES) and authorized to climb to flight level 140, though with specific restrictions due to existing traffic.
As the crew progressed through the climb and requested a direct route to the NEPIS position, they reduced their rate of climb to 500 feet per minute at flight level 120 to manage traffic. During this phase, the aircraft's Traffic Collision Avoidance System (TCAS) issued a Traffic Advisory (TA). Shortly after, upon reaching flight level 130, the system issued a Resolution Advisory (RA) with the instruction "LEVEL OFF, LEVEL OFF". The crew immediately executed the maneuver, stabilizing the aircraft at flight level 128.
Following the maneuver, a converging aircraft, a Boeing 737-800 operating as flight DWI 6263, crossed the flight path of FBZ 5062 at flight level 140. The crew of FBZ 5062 subsequently notified air traffic control of the TCAS event and identified the other aircraft.
The investigation
An investigation by the JST utilized radar imagery and communication records to reconstruct the proximity between the two aircraft. The data revealed a rapid decrease in separation: at 23:58:16 UTC, the aircraft were 7.4 nautical miles apart; by 2 minutes later, the distance had closed to just 0.70 nautical miles. At the moment the TCAS RA was triggered, the aircraft were separated by 1,000 feet vertically, with FBZ 5062 positioned below DWI 6263.
Findings
- The TCAS RA was triggered by the close proximity of a converging aircraft.
- The crew of the Boeing 737-800 (LV-KCE) successfully executed the required evasive maneuver.
- The second aircraft (DWI 6263) did not receive a TCAS RA and continued its planned climb without performing evasive maneuvers.
- No imminent collision occurred, as the separation between the two aircraft remained within the established legal margins for the airspace during the event.