BSNL MOVE COMES AFTER OFC LINK FAILURE AT KOLKATA AIRPORT ON 18 OCTOBER
By bappaditya paul
State-owned Bharat Sanchar Nigam Ltd (BSNL) is setting up a redundancy microwave link to Kolkata airport to ensure uninterrupted feed from various air surveillance apparatus and radars from different locations in eastern India in the event of a snap in the existing primary optical fibre cable (OFC) link.
The redundancy link is expected to become operational next week.
The move comes close on the heels of a BSNL OFC link failure on 18 October that had blacked out automated flight data transmission to the Kolkata Air Traffic Control (ATC) for nearly 10 hours; the controllers had salvaged the situation by falling back on an old mechanism that uses Very High Frequency (VHF) radio communication to locate and guide flights in the sky.
“Taking lessons from the incident, we have taken up two remedial measures. First, we are setting up a redundancy microwave link to the ATC building that will provide direct connectivity from our Dum Dum main exchange. Secondly, we are laying an OFC line interlinking the old and new terminals at Kolkata airport,” said Mr Asim Kumar Sinha, the spokesperson for BSNL’s Calcutta Telephones that serves the city airport.
Elaborating on the matter, Mr Sinha said that the existing OFC link to Kolkata ATC has “two circuits” for transmitting feeds from eight automatic dependant surveillance-broadcast (ADS-B) units and nine radar stations located at different places in eastern India (including one inside Kolkata airport). “We will provide two more circuits on the redundancy microwave link so that in the event of a failure in the primary OFC link, feeds to the ATC remains uninterrupted,” he said.
Calcutta Telephones has already started work on the microwave link that includes installation of a microwave system and antenna at the ATC and another dedicated antenna at Dum Dum exchange. “The work will be over in next two-three days and the redundancy link will hopefully to become operational latest by early next week,” the officer maintained. 
As regards interlinking Kolkata airport’s new and old terminal with an OFC line, the idea is to provide one more backup for the crucial flight operations and control services.
“We already have a microwave link to the new terminal and we are going to have a redundancy microwave link in the old terminal by next week. Now the idea is to interlink the two terminals with OFC so that in the event of a link failure in one terminal, the link from the other terminal will automatically shoulder the load and everything will run uninterrupted,” Mr Sinha explained. 
Kolkata ATC carries out very important functions vis-à-vis flight services over entire eastern India and parts of the north-west India. Besides handling the near 300 flights that fly in and out of the Kolkata airport every day, it also
monitors around 700-800 aircraft that over-fly the Kolkata Flight Information Region (FIR) daily.
(The author is on the staff of The Statesman, India. This report first appeared in The Statesman on 30 October 2014.)
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