A mid-air disaster was averted last week when a Visakhapatnam-Bengaluru IndiGo flight which was on a collision course with an Indian Air Force (IAF) aircraft over Chennai airspace steered to safety following an auto-generated warning, according to sources.

The two aircraft were just “300 ft” away from each other at the time of the incident on May 21 which set off a Resolution Advisory (RA) for the IndiGo pilot to steer the aircraft to a safer distance, sources said.

RA is an auto-generated warning in the cockpit for the pilot to manoeuvre the aircraft and avoid collision.

IndiGo confirmed the incident, which is now being investigated by aviation regulator Directorate General of Civil Aviation (DGCA). However, there was no response from the IAF.

“IndiGo aircraft VT-ITW operating on the Visakhapatnam-Bengaluru route and an Indian Air Force jet were on a collision course as the two aircraft were at a distance of just 300 ft from each other. The planes were at an altitude of 24,000 ft in Chennai airspace. IndiGo Airbus A320 flight was on the climb,” the source said.

The mishap was averted at around 9.49 pm on May 21, the source added.

“An IndiGo flight 6E- 647 (Vizag-Bengaluru) was involved in a resolution advisory at flight level 240, on May 21,” IndiGo said in a statement.

“Pilot followed the laid standard operating procedures,” the statement said, adding this matter was immediately brought to the notice of the regulator as per the prescribed protocol.

The incident is being investigated by the DGCA, it said.