Kolkata: A communication breakdown between Kolkata’s air traffic control and 85 airborne aircraft jeopardised lives of nearly 25,000 unsuspecting fliers for 10 minutes on Thursday. As multiple radars and vital VHF radio link failure continued for 1 hour 40 minutes, 35 controllers scrambled for mobile phones to contact nearby ATCs to alter flight levels of aircrafts. “What happened is a controller’s nightmare. Even landlines were not working. But, we managed to contact Nagpur and Varanasi ATC to relay information to pilots,” a controller said.
The Directorate General of Civil Aviation and Airports Authority of India said they would probe the incident, which started at 7.35am. The screens that display positions of aircraft in Kolkata air traffic region, which controls nearly half of India’s continental airspace, went blank. This shut the feed from aircraft tracking equipment six secondary surveillance radars and six allied equipment. The only radars that were functional were the ones at the Kolkata airport, Badu in North 24-Parganas and Berhampur in Odisha.
As per emergency protocol, the controllers turned to the very high-frequency communication sets to contact airborne pilots and instructed them to increase distances between successive planes. That is when they found the VHF lines, operated over internet protocol, were also down.
There were around 85 planes in the ATR when the communications failed. Of these, there were 30 planes that controllers had no control over. Compounding the problem, the controllers had lost touch with their counterparts in Dhaka and Myanmar as well. Controllers there help Kolkata ATC with west-bound international flights and eastbound overflights to Dhaka and Myanmar.
Though two frequencies were later restored, the range remained poor with controllers being able to speak to pilots at a distance of up to 130 nautical miles or till somewhere between Jamshedpur and Kolkata.
At 9.15am, the BSNLmaintained link was restored. Controllers have been calling for some private telecom operator’s services for their operations. But red-tapeism has led to dependence on BSNL.