A mid-air mishap was averted due to an auto generated warning after a SpiceJet aircraft came in close proximity of an overflying Emirates plane in the Indian airspace.
The incident which occurred on August 11, involving SpiceJet Hyderabad flight from Chennai (SG 511) and Emirates' Dubai-bound Brisbane flight (EK 433), is currently being investigated by the aviation regulator, DGCA sources said.
Earlier this month, a mid-air collision between two IndiGo planes, carrying over 225 passengers and crew, was averted over Dhaka airspace after the pilot of one of the flights steered away his aircraft to a safe distance when they came perilously close to each other.
According to sources, SpiceJet flight SG 511 was cleared for 34,000 ft and advised to standby to climb further.
"However, SG 511 climbed above the permitted level without clearance. It was then asked to maintain 35,000 ft but the aircraft overshot by a 1,000 ft, a level that EK 433 was maintaining," they said.
This forced the Emirates flight to climb further and increase separation, with both the aircraft receiving TCAS alert, sources said.
TCAS monitors the airspace around an aircraft for other aircraft equipped with a corresponding active transponder, independent of air-traffic control, and warns pilots of the presence of other transponder-equipped aircraft which may present a threat of mid-air collision.
"Emirates can confirm that flight EK433 Brisbane to Dubai on August 11, whilst in Indian airspace, received indications of proximity traffic. The flight crew correctly followed the on board system guidance to remain clear, following which they reported the occurrence to Air Traffic Control.
"At no time were passengers in any danger. The safety of our passengers and crew as always is our top priority," Emirates said in a statement.
However, according to SpiceJet sources, the ATC instructed it to climb and maintain 36,000 ft due to traffic at 37,000 level but "while passing flight level 35,000, ATC instructed the pilot to stop climb. By that time the aircraft had climbed to 35,400 feet. Our flight descended back to 35,000, and during which SpiceJet aircraft got descend resolution advisory."
Sources at the Directorate General of Civil Aviation said that the incident is being investigated and would soon be handed over to the Airprox Investigation Board.
As per the International Civil Aviation Organization, airprox is defined as a situation which, in the opinion of a pilot or air traffic services personnel, the distance between aircraft as well as their relative positions and speed have been such that the safety of the aircraft involved may have been compromised.
All the airprox incidents are probed by AIB constituted by DGCA and these investigations are reviewed at DGCA, headquarters for their completeness and process for implementation of recommendations, he said.
Airprox is a situation when two aircraft come dangerously close to each other.
As many as 17 airprox incidents, where two or more aircraft came close to each other while mid-air, were reported till July 10, the government had said in Parliament on August 4.