What happened
On January 30, 2016, at approximately 06:15 UTC, a serious air proximity incident occurred at Indira Gandhi International Airport in Delhi. Two aircraft, an Air India A320 (registration VT-EDD) and a Jet Airways B7 Im737 (registration VT-JBE), came dangerously close to one another during the landing phase of their respective scheduled operations.
The Air India flight, arriving from Shamshabad, was assigned to land on Runway 11. Simultaneously, the Jet Airways flight from Bengaluru was assigned to Runway 10. While the Air India crew initially reported being established on the Runway 11 localizer, the aircraft actually deviated from its assigned path. Instead of following the prescribed approach for Runway 11, the aircraft drifted toward the localizer for Runway 09. This deviation placed the Air India aircraft on a direct conflict course with the Jet Airways aircraft, which was established on the Runway 10 approach.
As the aircraft converged, the Current Conflict Warning (CCW) system triggered twice, indicating that lateral separation had dropped to approximately 1.2 NM and vertical separation had decreased to just 300 feet. To avoid a collision, the Aerodrome Controller instructed the Jet Airways aircraft to execute a go-around. The Air India crew also eventually initiated a missed approach after realizing they were aligned with the wrong runway. No injuries were reported among the 276 passengers and 14 crew members involved.
The investigation
The investigation conducted by AAIB India examined the flight paths, air traffic control (ATC) communications, and the operational environment at IGI Airport. Investigators looked into the technical settings of the airport's navigation aids, specifically noting that the localizer for Runway 09 remained active despite that runway being designated for departures only during the period of operation.
The inquiry also scrutinized the handoff procedures between Approach Arrival Control and the various Aerodrome Controllers (South, Middle, and North). The investigation reviewed the cockpit procedures of the Air India crew, specifically focusing on the programming of the Flight Management System (FMS) and the lack of cross-checking between the Pilot Flying and the Pilot Monitoring. Furthermore, the investigation assessed the ATC automation system's performance and the adequacy of existing Standard Operating Procedures (SOPs) for complex, three-runway operations.
Findings
- The primary cause of the incident was the selection of the wrong localizer runway by the Air India pilot.
- The Air India crew failed to re-verify the localizer frequency despite multiple reminders regarding their assigned runway.
- The localizer for Runway 09 was left in the 'ON' position, even though Runway 09 was only intended for departures.
- The Air India crew did not effectively cross-check the FMS entries, allowing the incorrect programming to go undetected.
- There was a lack of a mechanism to ensure minimum separation between aircraft once they were transferred from Approach Control to Aerodrome Control.
- The ATC automation system's conflict warnings did not immediately prompt effective corrective action from the controllers.
- The investigation identified a lack of documented SOPs specifically tailored for the complexities of three-runway mixed-mode operations.