At least two air traffic controllers (ATCs) were de-rostered as they were handling two planes which came close while manoeuvring over Delhi airspace earlier this month.
The ATCs were de-rostered as per standard procedure while necessary investigations were being carried out on the April 5 incident, Airports Authority of India sources said.
However, the AAI maintained there was "no serious collision risk" when the vertical separation between Air India flight IC-941 from Hyderabad to Delhi and Kingfisher Airlines' Delhi to Bhubaneshwar flight IT-3345 came down to 700 feet as against the required 1,000 feet when they were manoeuvring over Delhi airspace.
A conflict alert was generated at the ATC display when the Kingfisher plane was climbing to 17,500 feet and Air India aircraft was descending to 18,600 feet on April 5 when they were about 35 nautical miles south of Delhi.
"Both the aircraft at this stage were separated by 1,100 feet and seven nautical miles away from each other laterally as against the standard requirement of 1,000 feet in vertical dimension and three NMs laterally," the AAI said.
The two planes were also on "different flight paths" as one was approaching for landing and the other departing.
"Even though there was a breach of separation while executing the (collision) avoiding manoeuvres by the two aircraft, there was no risk of collision," the AAI said.
Meanwhile, Air India denied involvement of their aircraft in the incident and said in a statement that "as per our preliminary enquiries, no such incident has been reported by the operating crew".