Modernizing the Indian Airspace

Dec 2010 | One Comment

This is an introductory article focusing on communication navigation and surveillance systems in India

The Ministry of Civil Aviation, Government of India has the sovereign authority to modernize the Indian Airspace. Rapid strides have been made by the Ministry of Civil Aviation in implementing many elements of the Global Air Navigation Plan recommended by the International Civil Aviation Organisation (ICAO) for Communications, Navigation, Surveillance (CNS)/Air Traffic Management (ATM) systems. India is a founding member of ICAO and is a regional member of the ICAO Asia Pacific Air Navigation Planning and Implementation Regional Group (APANPIRG) based in Bangkok, Thailand.

ICAO and Global air navigation infrastructure

There are 199 Member States in the ICAO. The future Air Navigation System (FANS) Committee of ICAO has recommended the use of Global Navigation Satellite System (GNSS) in modernizing CNS/ATM systems. Any State that provides global air navigation infrastructure benefits by reduction in the overall cost of operation and maintenance of facilities as the traditional ground systems become obsolete and satellite technology is increasingly employed. They will also benefit from the enhanced safety. Modern CNS/ATM systems provide a timely opportunity for developing States to enhance their infrastructure to handle additional traffic with minimal investment.

The Asia-Pacific Region

Most Economies in the Asia Pacific Region weathered the recent economic downturn well and are growing rapidly again with India and China leading the growth. Half of the world’s civil aviation traffic added during the next 20 years is expected to be from or within the Asia Pacific Region. The total traffic for the region is expected to grow roughly at 7% per year during this period. Driven by economic development and the increasing accessibility of air transport services, traffic within the region will also grow faster than traffic to and from other regions. Discounting the slump in the growth of airline industry in the last two years, this industry is poised for rapid growth in the next two decades. The dramatic increase of air transportation industry in the Asia Pacific Region and a large economy like India requires a modern CNS/ATM systems.

Modern CNS/ATM

Modern CNS/ATM system is to employ digital technologies including satellite systems together with various levels of automation for CNS and as a strategic vision work towards a seamless global air traffic management systems that will enable aircraft operators to meet their planned times of departures and arrival and adhere to their preferred flight profiles with minimum constraints and without compromising agreed levels of safety. The ICAO global plan implementation would improve upon the present levels of safety, regularity, efficiency, capacity of airspace and airports, minimize fuel consumption and aircraft engine emissions, increase the availability of user preferred flight schedules and profiles and minimize differing equipment carriage requirement between regions. India is well on its way to implementing many elements of the ICAO plan.

• A modern CNS/ATM system improves Communications and hence the handling and transfer of information; improves Navigational accuracy leading to among other things reductions in separation between aircrafts and allowing for an increase in airspace capacity and extends Surveillance using the latest surveillance systems such as Automatic Dependence Surveillance (ADS). Advanced CNS systems will also see the implementation of ground based computerized systems to support increases in traffic. These ground based systems will exchange data directly with flight management System (FMS) onboard aircraft through a data link. This will benefit the ATM provider and airspace user by enabling improved conflict detection and resolution through intelligent processing, providing for automatic generation and transmission of conflict free clearances as well as offering the means to adapt quickly to changing traffic requirements. As a result, the ATM system will be better able to accommodate an aircraft’s preferred flight profile and help aircraft operators to achieve reduced flight operating costs and delays.

• ATM includes Air Traffic Service (ATS), Air Traffic Flow Management (ATFM), Air Space Management (ASM) and the ATM related aspects of flight operations. An effective ATM is essential to ensuring safety, regularity and efficiency of International Civil Aviation. The challenge for the planner and designer is to develop an adequate understanding of the cost, benefits and operational suitability of these alternatives while considering the legal, organizational, environmental and financial aspects.

Communication Navigation and Surveillance systems in India


In CNS/ATM systems, the transmission of voice will continue to take place over existing very high frequency (VHF) channels. However, the same VHF channels will be increasingly used to transmit digital data. Satellite Data and voice communications capable of global coverage are also being introduced along with data transmission over high frequency HF channels. The International Air Traffic Association (IATA) Member Airlines support VHF Data Link (VDL) Mode 2 as the communications infrastructure for Controller-Pilot-DataLink-Communication (CPDLC) at present.


The terrestrial navigational aids currently used in India and elsewhere are Non-Directional Beacon (NDB), Distance Measuring Equipment (DME) and Instrument Landing System (ILS). Improvements in navigation include progressive introduction of area NAVigation (R-NAV) capabilities along with Global Navigation Satellite Systems (GNSS).

These systems provide world-wide navigation coverage and are already being used for world-wide enroute navigation and non-precision approaches. With appropriate augmentation systems and related procedure it is expected that these systems will also support most precision approaches. The GNSS systems provide a high integrity, high accuracy, all weather world-wide navigation service with enhanced continuity and availability. The Indian Space-based Augmentation System (SBAS) is called GAGAN and when implemented in 2013 shall provide uniform navigational accuracies over the entire Indian Airspace. The ability for an aircraft to navigate in all types of airspaces in any part of the world are added advantages of the modern navigation systems. This does not mean that the conventional radio navigation aids are ready to be removed.


Traditional Secondary Surveillance Radar (SSR) modes will continue to be used. Gradually, SSR with mode S in both terminal areas and high density continental airspace will be introduced. The major breakthrough in surveillance technology is the implementation of Automatic Dependence Surveillance (ADS). ADS allows an aircraft automatically transmit its position, heading, speed and other useful information contained in the flight Management System (FMS) via a satellite or other communication link to an Air Traffic Control Unit (ATU). The position of the aircraft is displayed in a manner like that on a radar display. ADS is a true merging of communications and navigation technologies to provide surveillance. ADS along with ground system automation enhancements will allow for the introduction of significant improvement for ATM especially over oceanic airspace which lacks radar coverage. ADS-B (ADS-Broadcast) is a further improvement on the ADS technology wherein the aircraft disseminates its position not only to the ATC but to other aircrafts in its vicinity in its airspace. ADS-A/C is the latest advancement in the ADS technology and stands for ADS-Addressed or Automatic for ADS-A and ADS-Contract for ADS-C. ADS-A/C contains the software algorithms to transmit the position of the aircraft (either via SATCOM or VHF) every one to five minutes to an ATC listening station within the Fight Information Region (FIR). India has ADS-C facility over the Indian FIR including oceanic routes.

Indian Airports

India has 124 civil airports – 83 operational and 41 non-operational airports. 5 more airports are likely to be made operational by 2011. All airports have VHF Omni-directional Range (VOR) and Distance Measuring Equipment (DME). There are 99 domestic and 79 international ATS routes in and out of the country which operate through more than 80 civil airports in India. There are 14 Monopulse Secondary Surveillance Radars (MSSRs), 8 Primary Surveillance Radars (PSRs) in S-band and 2 primary radars in L-band. Out of these, 6 airports (Delhi, Mumbai, Bangalore, Hyderabad, Chennai and Kolkata) carry more than 90% of the revenue earning traffic and command more than 90% of the passenger traffic. 38 stations are being upgraded to be provided with ATC automation systems with the capability of integrating data (Radar and Flight plan data with the main systems at Chennai, Kolkata, Mumbai and Delhi systems). All of these airports are equipped with Instrument Landing System (ILS). There are over 400 passenger aircrafts in the country today and according to one estimate the additional no. of aircrafts needed over the next 2 decades is about 900.

[The Indian Flight Information Region (FIR) is supported by ADS-C. Delhi has category-IIIB Landing facility, Kolkata and Lucknow have Category-II and the Airports Authority of India plans to install 7 Cat.I ILS equipment, 3 Cat.III ILS and 2 Cat.III ILS at Amritsar, Jaipur, Jammu, Delhi, Mumbai etc. The number of tourists visiting India has increased from 10 Million in 2005 to 17 Million in 2010 and is slated to increased to 25 Million in 2013. Large airports in India such as, Delhi and Mumbai are being planned to handle a capacity of 100 Million passengers per year].

Performance Based Navigation (PBN)

In conventional navigation, the aircraft uses the ground based terrestrial navigation aids for position determination and flies from its departure point to destination point with reference to the air traffic control points. The flight path is, therefore, fixed . In Performance Based Navigation (PBN) the aircraft determines its position from Global Navigation Satellite Systems (GNSS) which is integrated into the on-board navigation and flight management system. This allows the pilot to fly an efficient and flexible path to its destination. Area Navigation (ARNAV) and Required Navigation Performance (RMP) are two constituents of PBN. Airports Authority of India (AAI) has adopted an integrated approach towards implementation of PBN procedures. Efficient implementation of PBN will result into enhanced airspace capacity, enhanced safety, repeatability of flight path, reduction in controller pilot communication, reduced fuel burn and reduced reliance on ground based navigation infrastructure.

Benefits of modern CNS/ATM systems to Airlines, States and environment

A modern CNS system will enable airlines to fly the aircrafts with reduced separation standards over all oceanic airspace with reduced vertical separation for more dynamic and direct routing with an overall enhancement of safety. For States which introduced the modern CNS/ATM systems, the overall cost of operation and maintenance of ground infrastructure is expected to reduce, timely introduction of these modern systems will help enhance the States infrastructure to handle additional traffic with minimal investment. It will also permit better upper Airspace management and bring in to the basket of greater access to unusable airspace. As the Aviation industry grows more and more the impact of air traffic operations on the global atmosphere becomes increasingly important in addition to the local affects of noise and air quality. Improved ATM could help reduce aviation fuel burn and thereby reduce the levels of aircraft engine emissions.

The indirect benefits are lower fares and passenger time savings, transfer of high technology skills, productivity improvements and industry restructuring, stimulation of related industries, enhanced trade opportunities and increased employment.

Green fields airports

The Ministry of Civil Aviation has formulated a policy for Green-field airports development. By definition, a green-field airport is an infrastructure created in a place where no CNS/ATM facility existed earlier. Introduction of GNSS based CNS/ATM assists in providing advanced CNS/ATM services to green-field airports at a relatively low cost and the aircraft carries a certified CNS system.

Suresh V Kibe

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ISRO HQ, Bangalore, India.
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One Comment »

  • crazymotts said:

    Good to learn about the attempts to implement satellite-based navigational systems and procedures in commercial aviation. Airspace management would get a whole new dimension with the implementation of GNSS-based navigation systems.

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