The blind eye in the sky

It is understood that a bid is being made for such planes for the Indian Air Force. The IAF has to lay down priorities. Understandably, the first priority is for surveillance in the border areas so as to prevent intrusion. Next comes surveillance to provide in-depth defence to protect sensitive areas. Resources generally get exhausted while meeting these requirements, leaving large chunks of airspace in the interior of the country without radar surveillance. However, the AWACS, besides bridging these radar gaps, is also a major force multiplier.

The Airport Authority of India is responsible for air traffic services in the five flight information regions which fall in India’s jurisdiction. Out of this airspace, more than 60 per cent is oceanic, where conventional radar surveillance is not feasible. Even in the remaining continental airspace where radar surveillance is feasible, only about 10 per cent of the airspace is presently covered by credible radar surveillance. In contrast, almost the entire air route structure in Pakistan has effective radar surveillance.

This is not to say that the picture, which was dismal till recently, is notchanging fast, as the AAI’s countrywide programme for modernisation is underway. The programme involves establishing new generation primary radars with a range of 60 nautical miles and secondary radars with a range of 240 nautical miles at eight airports — Ahmedabad, Calcutta, Delhi, Guwahati, Hyderabad, Madras, Mumbai, Trivandrum. In addition, Delhi and Mumbai will have primary radars with a range of 240 nautical miles. Even then, the surveillance cover will be inadequate to cover all air routes and at all heights. The AAI’s original plan to install radars at 24 locations to bring the entire Indian subcontinental airspace under surveillance for all aircraft flying above 10,000 ft has been put on hold. Two points are worth noting. First, radar surveillance will be available only on aircraft flying above 30,000 ft. Second, secondary radars, not primary radars, will cover most of the area.

Secondary radars carry out all the functions of primary radars and some more (like providing aircraft identity and height) and are about three times cheaper. The only hitch is, a secondary radar operates in conjunction with transponders installed on-board aircraft. Hence, secondary radars require a cooperative environment. A pilot can make his aircraft completely disappear from the radar screen by simply switching off his transponder! Though a highly suitable and cost-effective air traffic service, the secondary radar cannot prevent a deliberate violation of airspace. In fact, a secondary radar creates a false sense of security while transforming every aircraft of the potential troublemaker into a Stealth aircraft free of cost! The concept of automatic dependent surveillance (ADS), which is a key element of future air navigation system (FANS), also provides the facility for any pilot to make his aircraft disappear from the air situation display screens at any time at his will.

Secondary radars and ADS will serve the cooperative environment of the civil aviation sector well, but will do little to ensure national security. Primary radars will detect intruders positively and are therefore vital for national security. The very same primary radars will provide weather detection capability which the secondary radars do not have, and thus improve air safety.