What happened
On February 2, 2024, at Veer Savarkar International Airport in Port Blair, a serious air proximity incident occurred between an Air India A319-112, registration VT-SCV, and an Indian Navy ALH MK III helicopter, call sign Examiner 7.
While the Air India flight was preparing for departure on Runway 2/2, the Navy helicopter was performing a training mission, specifically an overhead ILS approach for Runway 04. The Approach Controller cleared the helicopter to proceed outbound, which placed it directly in the intended takeoff path of the departing Airbus. Although traffic information was provided to both aircraft, the faster-climbing A319-112 caught up to the helicopter at approximately 2,700 feet.
In response to a TCAS Traffic Advisory, the helicopter pilot executed a right turn to avoid the collision path. Simultaneously, the crew of VT-SCV visually identified the helicopter through the right windshield. Believing the aircraft was in immediate danger, the Air India pilot initiated an aggressive nose-down maneuver, descending at 2,800 feet per minute. This sudden descent caused the aircraft speed to surge to 245 knots, triggering a VFE overspeed warning.
The investigation
AAIB India examined the actions of both the air traffic controllers and the flight crews. The investigation focused on the coordination between Tower and Approach controllers and the limitations of the surveillance equipment in use. Investigators also reviewed the radar data and radio transcripts to reconstruct the sequence of events.
Findings
- The inadequate assessment of the traffic situation by the approach controller was the primary cause, as the controller failed to recognize that the actual aircraft sequence differed from the expected one.
- The Approach Controller did not verify the exact position of the helicopter when it reported being overhead.
- The use of primary surveillance radar at the aerodrome limited the controller's ability to monitor the helicopter, as the radar blip was lost during the outbound leg.
- The Air India crew acted based on visual contact rather than TCAS alerts, as the aircraft's onboard systems did not generate a Traffic Advisory or Resolution Advisory.
- The aggressive avoidance maneuver by the A319-112 crew resulted in an overspeed condition.
- There is currently no formalized mechanism for the exchange of safety-related information between Indian Defence authorities (Navy, Air Force, Army) and the AAIB/DGCA.
Safety action
- It is recommended that the Indian Navy consider implementing a secondary radar system at Port Blair to improve traffic management.
- A formal framework for collaboration between the DGCA/AAIB and Defence authorities should be established to ensure effective safety investigations.
- The DGCA should review investigation procedures to include occurrences involving defence aircraft or aerodromes.
- Air India is advised to reinforce radio telephony discipline among its flight crews.