2023 near-miss probe: DGCA to check carriers’ nav systems

THe Aircraft chance event investigating Bureau (AAIB) has asked the board of directors superior general of civic Aviation (DGCA) to inspect all scheduled airlines and the air navigation services provider to assess their safety management systems. The recommendation follows a near-miss involving two IndiGo aircraft over Delhi in 2023.In its final report -- published on Wednesday -- the AAIB said safety margins dropped to dangerously low levels moments after takeoff during airprox (air proximity) incident at Delhi’s Indira Gandhi International Airport on the November 17, 2023. This triggered collision avoidance alerts, averting a potential major accident.Besides DGCA inspections, the AAIB asked IndiGo to ensure correct Flight Management and Guidance System (FMGS) entries, avoid cockpit disturbances during setup and enforce comprehensive cross-checks during training. FMGS is an integrated avionics system in Airbus aircraft that automates flight planning, navigation, and trajectory control.It also stressed the need to monitor post-takeoff trajectories and maintain operational discipline during simultaneous runway operations at busy airports such as Delhi.The report also noted that strict adherence to TCAS procedures is crucial to prevent accidents when safety margins erode rapidly.The incident involved IndiGo flight 6E 2113 (Delhi-Hyderabad) and flight 6E 2206 (Delhi-Raipur). Both Airbus aircraft departed within seconds of each other from different runways after receiving ATC clearance.VT-IUO (6E 2113) was cleared to depart runway 27 and follow its Standard Instrument Departure (SID) — a pre-defined manoeuvre ensuring safe climb. However, it deviated towards the corridor of runway 29R, from where VT-ISO (6E 2206) had just departed and was climbing.This caused a serious loss of separation. The AAIB found the vertical gap dropped to 400 feet and the lateral distance to 1.2 nautical miles — breaching the mandatory 1,000 feet and five nautical miles required in controlled airspace.The breach triggered ATC alerts and Traffic Collision Avoidance System (TCAS) warnings in both cockpits. The report credited the pilots’ timely response to the TCAS advisories — which provide commands to avoid conflicting traffic — for preventing a collision.There were no injuries or damage to the aircraft.The bureau attributed the incident to VT-IUO’s deviation from its SID, which caused it to infringe on the separation required from the other aircraft in congested airspace.