What happened
On 04 March 2022, Pakistan International Airlines flight PIA303, an Airbus A320-214 with registration AP-BOL, was operating a scheduled passenger service from Lahore to Karachi at Flight Level 380. Simultaneously, a Pakistan Navy Hawker Beechcraft aircraft, GHAURI-62, was climbing through the same airspace toward Flight Level 390.
Approximately 30 nautical miles northeast of Nawabshah, both aircraft triggered Traffic Alert and Collision Avoidance System (TCAS) Resolution Advisories (RA). The AP-BOL crew initiated an RA climb to FL385, while the GHAURI-62 crew performed an RA descent to FL374. At the moment the advisories were issued, the aircraft were separated by only 200 feet vertically and 6.2 nautical miles laterally.
The investigation
The Bureau of Aircraft Safety Investigation (BASI) determined that the ACC Radar Controller (East) had left his duty position for a personal break at 06:50 UTC, assuming the Procedure Controller would manage the radar traffic. At the time, the position was being manned by a trainee controller undergoing On-the-Job Training (OJT). The investigation found that the Procedure Controller was simultaneously engaged in coordinating a military exercise, which led to divided attention.
Findings
- The primary cause of the incident was the absence of the ACC Radar Controller East from his radar executive position.
- The TCAS-RA was activated due to a lack of situational awareness by the ACC Procedure Controller.
- The Procedure Controller re-cleared GHAURI-6A to FL390 without considering the conflicting PIA303 at FL380.
- Contributory factors included a lack of supervision by the Procedure Controller (acting as OJTI) due to simultaneous training and coordination tasks, as well as insufficient involvement from the Team Leader.