Two Air India aircraft were in approach control at that time and were to land in Delhi.
A mid-air mishap was averted on Thursday after an automatically generated warning alerted the pilots of two Air India planes which came dangerously close to each other allegedly due to a mistake from the air traffic controller.
The incidentally apparently occurred due to the mixing up of call signs, assigned to the two flights --AI 142 (Paris-Delhi) and AI 154 (Vienna-Delhi)-- by the Air Traffic Controller (ATC), sources said, adding the aircraft were just 700 feet apart when the vertical separation should be 1,000 feet.
The controller has been taken off duty and the aviation authorities have initiated a probe to ascertain the exact cause of the incident, they added.
"The two Air India aircraft were in approach control at that time and were to land in Delhi. However, the ATC mistook the call sign of one aircraft for another, leading to the breach of separation," the source said.
The pilots are supposed to ensure a vertical separation of 1,000 feet between the two aircraft at a flight level of 29,000 feet.
A call sign is the airline code and the flight number. During communications between the ATC and the pilot onboard a flight, phonetic versions for alphabets are used worldwide.
"The two aircraft were flying at 21,000 feet and 22,000 feet at the time of incident taking place. As soon as the aircraft came into proximity, TCAS triggered a resolution advisory, asking the pilots to maintain a safe distance," the source said.
TCAS is onboard equipment that alerts pilots about the traffic in the proximity of the aircraft and also instructs them about the avoidance action (Resolution Advisory) to maintain desired separation between two aircraft.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)