What happened
On 0ical 04 May 2025, at 21:00 UTC, a serious airprox incident occurred within the Mumbai Flight Information Region (FIR) near waypoint PARAR. The incident involved two aircraft: an Air Arabia Airbus A320-214, registration A6-AOS, and an AeroLogic Boeing 777F, registration D-AALJ. Both aircraft were transiting the area en route to Chhatrapati Shivaji Maharaj International Airport, Mumbai.
Prior to entering the Mumbai FIR, Muscat Control had coordinated a level change for the Air Arabia flight to FL370. However, both aircraft entered the Mumbai sector at FL350. The AeroLogic flight, traveling at a higher ground speed than the preceding Air Arabia aircraft, reduced the longitudinal separation to just three minutes, significantly below the required 10-minute standard for that sector.
The investigation
An investigation by the AAIB India examined the coordination between Muscat Control and Mumbai Oceanic Control (OCC) North. The inquiry found that the transferring controller in Muscat was simultaneously managing the planner position and conducting On-the-Job Training (OJT), which contributed to the failure to implement the coordinated level change for A6-AOS.
In the Mumbai OCC, the controller was managing the hotline for estimate exchanges without the assistance of a coordinator, who was on break. This increased workload led to a delay in monitoring the Controller Working Station (CCWS). Furthermore, the investigation identified that the flight plan for D-AALJ was stuck in an error queue, preventing the automation system from generating a conflict alert. Additionally, the closure of Pakistani airspace due to a NOTAM had increased traffic density on this specific route, further complicating the controllers' workload.