The spate of aerial mishaps in India can make anyone quake in his boots while boarding an aircraft. The tragic Mangalore crash along with a serial bunch of near misses has put the spotlight on safety in Indian skies. Experts have questioned India?s airline safety record and there seem to be more questions than solutions on this front.
At this juncture, the Airports Authority of India (AAI) and Indian Space Research Organisation (Isro) have come together to create a unique navigation platform. The satellite-based augmentation system (SBAS) is slowly becoming the talk of the aviation town. The final operation phase of the country?s GPS-Aided Geo Augmented Navigation (GAGAN) was formally launched recently by civil aviation minister Praful Patel, raising new expectations on the safety front.
The GAGAN system, being developed by AAI and Isro, envisages a network of ground stations and satellites that would ensure greater navigational accuracy and also continuity of signals for aircraft. This system will not become operational for civil aviation until June 2013, but signals from the system for non aviation uses such as surveying or search and rescue are expected to be available as early as March next year once the space component is in place.
A satellite-based augmentation system helps pilots check the accuracy of the GPS data they receive and alerts them about a correction within six seconds. It would also render easier the task of aircraft separation for air traffic controllers besides saving costs on instrument landing systems on runways.
The need for a satellite based augmentation system arises because the current GPS constellation cannot support requirement for all phases of flight and the integrity is not guaranteed as satellites are not monitored at all time.
The technology demonstration phase of the Rs 700-crore project was completed in 2007 as part of which eight ground stations were installed at different airports across the country. A total of 15 stations will make up the ground segment.
The space component of the system comprises three payloads in a geostationary orbit. These satellites will help in getting signals corrected according to the accuracy specified by the International Civil Aviation Organisation. The first of the payloads was slated for launch on the GSAT-4 satellite, but the failure of the launch vehicle GSLV D3 in April has caused a setback.
According to the AAI?s roadmap, the space payloads are expected to be in place by November. To meet civil aviation requirements, however, it would take at least two years of testing to get certification from the Directorate General of Civil Aviation, the country?s civil aviation regulator.
In the GAGAN system, data received from the global navigation satellite system will be processed at the 15 ground stations . The data would be forwarded to three mission control centres where it would be processed to determine corrections for each monitored satellite and for each pre-determined ionospheric grid point.
This information would be uplinked via three Indian navigation uplink stations to the GAGAN satellite, which in turns downlinks the data to users via two L-band ranging signal frequencies. The GAGAN system will provide augmentation service for GPS over India, Bay of Bengal, Southeast Asia the Middle East and upto Africa.
According to the civil aviation ministry, it will be compatible and interoperable with other SBAS systems such as the Wide Area Augmentation System of the USA, the European Geostationary Navigation Overlay System of the European Union and Japan?s Multifunctional Satellite Augmentation System. GAGAN will fill the gap between the European and Japanese systems to provide seamless air navigation service across regional boundaries.