What happened
On March 18, 2022, at approximately 04:57 UTC, an air traffic incident occurred in Chilean airspace on the UL302 airway, roughly 60 nautical miles south of the IREMI intersection. The event involved two aircraft operating in opposite directions: a LAN Peru flight, LPE2371, traveling from Lima to Santiago, and an American Airlines flight, AAL908, traveling from Buenos Aires to Miami.
At the time of the incident, LPE2371 was cruising at flight level 350. The pilot requested an ascent to flight level 370. Meanwhile, AAL908 was maintaining flight level 360. Following the authorization of the climb, the two aircraft crossed paths at flight level 360, resulting in a loss of required separation. Radar data from Peru later confirmed that the aircraft were approximately 29.5 nautical miles apart when they encountered each other at the same altitude.
The investigation
The investigation by DGAC Chile focused on the actions of the Oceanic Area Control Center (ACCO) personnel. Investigators examined the flight progress strips, radio communications, and radar imagery provided by CORPAC-Peru. The investigation noted that at the time of the event, the air traffic controllers in charge were a trainee controller and a facilitating controller (who was also the shift supervisor).
Investigators found that the trainee controller was managing multiple tasks, including handling satellite communications and coordinating with other sectors. During this period, the controller failed to complete the necessary crossing time calculations for the two aircraft. Furthermore, the investigation revealed that the radar coverage in the specific sector was insufficient, meaning the controllers were not viewing the aircraft on their radar presentation at the moment the separation was lost.
Findings
- The trainee controller issued an authorization for LPE2371 to climb to flight level 370 without verifying the position of AAL908.
- The facilitating controller failed to provide adequate supervision or monitor the traffic situation effectively.
- The lack of supervision by the facilitating controller was a primary factor in the incident.
- There was a lack of continuous radar coverage and communication stability in the IREMI and ASEPU sectors.
- The controller did not record or communicate the estimated crossing time on the flight progress strips.
- Neither aircraft reported an activation of the Traffic Alert and Collision Avoidance System (TCAS).