The transition to CNS/ATM systems will be one of the largest undertakings ever carried out by the aviation community, not only because of the immense scale of the change but also because the transition will fundamentally affect how aviation administrations provide air traffic services. A broad indication of how the transition might proceed is as follows:
1999
Continuing developments, trials and pre-operational demonstrations. Present-2000. Gradual implementation and use of various elements of the system. Some aircraft and administrations will use the CNS/ ATM systems with backup from the terrestrial systems.
2000-2005
Full CNS/ATM services available in parallel with existing systems so that appropriately equipped aircraft can have maximum operating benefits from the CNS/ATM systems.
2005-2010
The international terrestrial system not required for the CNS/ATM systems progressively dismantled.
2010
The CNS/ATM systems are the sole systems for international use. In any such transition timetable, there will be a period when the CNS/ATM systems and the existing terrestrial systems are operating in parallel. While this period allows for aircraft operators to change their equipment, and for service providers to phase out those ground facilities which will no longer be required, maintaining two systems is very costly. The costs associated with the transition are therefore an important component of the economic assessment of the CNS ATM systems.
Table: 1 CNS Systems Evolution
| Airspace | Function | Current system | Future System |
| Oceanic continental En-route airspace with high / low-density traffic | Navigation
Communications
Surveillance | OMEGA/LORAN-C NDB VOR/DME Barometric altimetry INS/IRS
VHF voice
VF voice
Primary radar/SSRVoice position reportsOMEGA/LORAN-CNDB | RNAV/RNPGNSSBarometric altimetryGNSS altitudeINS/IRS
VHF voice/ data AMSS data/voice HF voice ; North and South poles only
ADS
RNAV/RNPG NSS |
| Continental airspace with high-density traffic | Navigation
Communications
Surveillance | VOR/DME
Barometric altimetry
INS/IRS
VHFvoice
Primary radar
SSR Mode A/C | Barometric altimetry GNSS altitude
INS/IRS
VHF voice/data AMSS data/voice SSR Mode S data link
SSR[Mode A/C orMode S]
ADS |
| Terminal areas with high-density | Navigation
Communications
Surveillance | NDB VOR/DME ILS Barometric altimetry INS/IRS
VHF VOICE
Primary radar
SSR Mode a/c | RNAV/RNP
GNSS
MLS
NDB
VOR/DME
Barometric altimetry
INS/IRS
VHF voice/data
SSR Mode S data link
AMSS data /voice
SSR [Mode A/C or Mode S] ADS |
Evolving Ground Infrastructure
The Aeronautical Telecommunication Network (ATN) is being defined within the International Civil Aviation Organization (ICAO) as a digital data communications network for the aeronautical community. The ATN is a key component of the Future Air Navigation System (FANS) which includes enhanced communications, navigation, and surveillance capabilities necessary to improve the efficiency of the global air traffic management system.
The ATN will allow the interconnection of a diverse collection of air-to- ground and ground-to-ground communications systems to provide global information transfer among computers used for air traffic management, airline operations, general flight information services (such as weather), and passenger services. Building the ATN requires special communications components, called ATN routers, both in the aircraft and on the ground.
These routers will interconnect the various communications systems and ensure that communications paths between all users, including aircraft in flight, are available throughout the network.
Implementation of FANS and the ATN will result in major benefits to both the public and private sectors. Benefits to civil aviation authorities and airspace users will include reduced costs for communications services through increased competition and the use of shared networks, and increased communications reliability and capacity.
The major benefits of FANS will come from the more efficient use of the airspace allowed by improved automation and communications. In 1994, the FAA outlined the incremental changes in air traffic control procedures for aircraft that will be possible with FANS equipment, including ATN, operating over the oceans. Those changes included reduced separation standards, reduced mandatory
fuel reserves, and more efficient routes for equipped aircraft.
Efficiency Benefits due to CNS ATM
- The improved navigation, communications and surveillance brought about by implementation of CNS/ATM will allow more direct routing of aircraft, which will generate savings in fuel cost and other aircraft operating costs. The amount of these savings will depend on the reduction in the number of aircraft-hours flown in the airspace as a result of CNS/ ATM and on aircraft operating costs per hour.
- Communications and navigation improvements, which
produce more direct flight paths and less delay from airspace
congestion, will reduce the passenger travel time for a given
journey. If passengers value these time savings, they
represent an additional benefit.
- FANS will revolutionize the economics of airline operations whilst offering enormous benefits to air traffic control agencies, as well as to national economies.
- Through FANS implementation, the rising demand for air travel will be met and at a higher level of safety than possible today.
- Congestion and delays should decrease, with airport and airspace capacity being used as efficiently as possible.
- Airlines will be able to fly more efficient routes, thus reducing their fuel and other operating costs.
- Air navigation service providers will be able to reduce the number of expensive ground based navigation aids, realizing savings. Improved air transport efficiencies will make a positive contribution to economies; opportunities for travel, tourism and cargo shipment will increase, even as airlines reduce the environmental impact of each flight.