A major tragedy was narrowly averted, thanks to technology, which prevented a mid-air collision between two IndiGo planes at Delhi Airport. According to a report by the Times of India, the aircraft came dangerously close to each other seconds after take-off from the airport in November 2023.
The preliminary report from the Aircraft Accident Investigation Bureau (AAIB) revealed that one of the aircraft turned in a direction it was not supposed to, putting it on a collision course with another plane that had just taken off from a different runway at Indira Gandhi International Airport (IGIA).
The Traffic Alert and Collision Avoidance System (TCAS) alerted both flights, prompting them to change their courses to avoid each other.
On November 17, 2023, an Airbus A321 (VT-IUO) was scheduled to operate as 6E-2113 to Hyderabad and an A320 (VT-ISO) as 6E-2206 to Raipur. 6E-2113 received departure clearance from runway 27 and took off at 12:31 pm. "It established contact with (ATC), which cleared it to climb to 8,000 feet. However, 6E-2113 was observed turning left toward the take-off path of runway 29R instead of (the assigned path). At the same time, 6E-2206 received clearance and departed from runway 29R... climbing to 4,000 feet," according to the preliminary report of AAIB, as reported by TOI.
"6E-2206 came into contact with (ATC), and the controller instructed it to climb to 4,000 feet. During this sequence, a breach of separation occurred between 6E-2113 and 6E-2206, triggering a conflict alert at 12:31:43 pm. Both aircraft received TCAS-RA," the report says.
At the time of the closest vertical separation (400 feet), lateral separation was 1.2 nautical miles (NM). At the time of the closest lateral separation (0.2 NM), the vertical separation was 800 feet. There were no injuries to any occupants on board either aircraft, and there was no damage, the report adds.