Planes a blip from collision

An Airbus with 136 passengers on board and an inbound cargo jet that had dropped to the same altitude were so close to each other two weeks ago that the two blips representing the aircraft on the radar actually merged.
Blips representing planes merge on the radar when the horizontal distance between them is 10 km or less. A distance of 10 km might seem reasonable, but that could have been covered in a minute by jets travelling at approximately 600 kmph.
The Air India Airbus A-320 was flying to Agartala and the Boeing 737 cargo carrier, owned by Alliance Air, was coming from there to Calcutta. The planes came within sniffing distance of each other 60 nautical miles from the city airport, after the pilot of the cargo jet had descended 1,000 feet more than what Air Traffic Control (ATC) recommended.
The cargo jet was at 24,000 feet when ATC personnel asked its pilot, said to be a veteran, to descend to 18,000 feet and await further communication. The other aircraft had maintained the specified altitude of 17,000 feet.
Aviation officials who did a “radar replay” on Tuesday wondered how the pilots of the planes avoided a repeat of the 1996 mid-air collision off Delhi that killed 349 people.
Aviation experts suspect the two planes were a fraction of a second away from colliding when the pilots changed course.
“It is unbelievable that two planes came so close to one another and did not collide,” an ATC official said.
The ATC official said the planes would certainly have collided had the Traffic Collision Avoidance System that is installed in all modern aircraft malfunctioned.
11/06/08 Sanjay Mandal/The Telegraph

To Read the News in full at Source, Click the Headline

Categories: Air India - International Jun 2008, Air India Regional Jun 2008, dome, Safety Jun 2008