Incident Overview
On January 5, 2022, at approximately 03:29 UTC, an air traffic incident (AIRPROX) took place 35 nautical miles south of the SORTA intersection on upper airway UL780 in Chilean airspace. The incident involved two Boeing aircraft: flight AAL940 (from Santiago to Dallas Fort Worth) and flight DAE1557 (from Miami to Santiago). Neither aircraft sustained damage, and no injuries were reported.
Relevant Flight Details
Flight AAL940 departed Santiago (SCEL) at 22:30 local time (01:30 UTC) en route to Dallas Fort Worth (KDFW) at flight level (FL) 360. The crew estimated crossing SORTA at 03:34 UTC. Flight DAE1557 departed Miami (KMIA) for Santiago at FL350, with an estimated SORTA crossing at 03:24 UTC.
Air Traffic Control Actions
The Oceanic Area Control Center (ACCO) controller had received a handover of traffic at 03:02:55, which included both flights. At 03:10:42, the controller instructed AAL940 to report position SORTA on Lima Control frequency 128.8 MHz, though the flight remained under the controller's jurisdiction until leaving the area. At 03:26:53, DAE1557 reported crossing SORTA and requested climb to FL370. The controller, as later acknowledged, authorized the climb without realizing that AAL940 was at FL360 in opposite direction.
Resolution
At 03:30:07, DAE1557 called the controller and reported a Traffic Alert and Collision Avoidance System (ACAS) Resolution Advisory (RA) while climbing to FL370. At 03:36:44, Lima Control contacted the ACCO controller, informing that AAL940 had reported a TCAS RA and had climbed 500 feet to FL365. Both controllers noted that radar coverage was lost in the area at the time of the crossing.
Weather Conditions
The incident occurred at night under visual meteorological conditions (VMC).