India has awarded Raytheon an $82 million contract to deploy a GPS-aided geosynchronous augmentation system (GAGAN) that should allow the country to begin using satellite-based instrument landing capabilities in the 2014 timeframe.

In the US, such approaches are known as lateral precision with vertical guidance (LPV).

The system will use two geosynchronous satellites to be built and launched by the Indian Space Research Organisation (ISRO), the equivalent of NASA in the US, and one master station and eight ground reference stations to be provided by Raytheon.

Raytheon is leveraging its knowledge in building, deploying or developing four other GPS augmentation systems to date, including the wide-area augmentation system (WAAS) in the US, Japan's Multi-Function Transport Satellite Augmentation System and the Joint Precision Approach and Landing System for the US military.

Augmentation systems gather positioning information from existing global positioning networks like GPS or Galileo, calculate signal corrections to account for accuracy-reducing atmospheric perturbations, and retransmit modified signals to GPS-receiving equipment onboard aircraft.

As in the US, GAGAN will be designed to provide a guaranteed "uncertainty bound" of 50m (164ft) worst case, a specification set by ICAO to ensure that an aircraft will have adequate ground clearance at the decision height of 250ft above the ground on an LPV approach. Worst case conditions are expected to occur on an extremely rare basis.

In general, the Indian augmentation system will provide positional accuracies of roughly 3m, the same as for the US.

Raytheon in 2007 completed a $25 million technology demonstration of the system in India, proving out the ground station and communication strategy.

Raytheon will begin deploying the GAGAN ground infrastructure in 2012, with plans to make the system operational in 2013. Airlines will begin equipping aircraft with global positioning system receivers in 2014.

Source: Air Transport Intelligence news