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dog to provide guidance to blind people to the car navigation and traffic management systems
based on satellite navigation. And in the civil aviation sector from offer of shorter routes, quicker
access to airports and final approaches and landing at most airports according to CAT 1
requirements. Precision approaches CAT3 will probably not arrive before the year 2010.
Document prepared by EVP Europe, August 1999 Page 4 of 14
2. CNS/ATM1
CNS/ATM as defined by ICAO is “Communications, Navigation and Surveillance systems,
employing digital technologies, including satellite systems together with various levels of
automation, applied in support of a seamless global Air Traffic Management system.” There is no
unique CNS /ATM solution; there are a variety of CNS/ATM – related implementations, which all
contribute to the CNS/ATM global goal. The challenge is to define an implementation that allows
benefits and return on investment to be achieved as rapidly as possible. In the near-term this is
best achieved by looking at the CNS/ATM elements using two simple constraints: what exists
now and what is likely to exist over the next years.
Communications for CNS/ATM is digital-based and data link is an augmentation of voice
communications for the next five years. Terrestrial-based VHF Data Link (VDL) is well suited for
the en-route, terminal and airport area where line-of-sight systems can be used. VDL is used
today for ATM functions such as Pre-Departure Clearance (PDC), Departure Clearance (DCL),
Digital Automatic Terminal Information Service (D-ATIS), Terminal Weather Information for Pilots
(TWIP) and other ATM functions. Satellite and HF data links are more suitable for oceanic and
remote areas where VDL is not available. Satellite and HF will continue to be provided by private
service providers whereas private service providers or other authorities may supply VDL.
Area navigation (RNAV) capability allows Air Navigation Service Providers (ANSPs) to offer the
most cost-effective solutions to airspace users. GNSS support highly accurate RNAV (sic.
almost) 2everywhere, including over the oceans and in remote areas. GNSS avionics are
relatively inexpensive, so all levels of users can participate in RNAV operations, thus allowing
ANSPs to structure airspace for maximum capacity. GNSS also gives airspace designers a
future option in developing procedures that support low minima, avoid noise sensitive areas and
reduce flying time in the terminal area (4D NAV).
Ultimately, GNSS could replace all traditional aids, although there are still technical, operational
and institutional issues to be resolved before reaching this goal. Core navigation satellites, GPS
and GLONASS, are already in service with many operators using GPS for en-route through nonprecision
approach operations. A ”sole means” GNSS environment requires ANSPs to field
Satellite-Based and Ground- Based Augmentation Systems (SBAS and GBAS). SBAS and
GBAS that meet ICAO standards will become operational within the 5-year period.
Over the next 5 years and longer it is expected that both primary and secondary radar will
continue to be used, supplemented by Mode S data link where appropriate. Remote and oceanic
areas will see increased use of Automatic Dependent Surveillance (ADS) to supplement and
eventually replace today’s voice-based position reporting in procedural airspace.
The airframe manufacturers, Airbus and Boeing, market their near-term implementations of
CNS/ATM as FANS Avionics packages. Airbus advertises the FANS-A; Boeing advertises the
FANS-1. FANS-1/A is an initial implementation of CNS /ATM, which provides a subset of the
ICAO-defined ADS and CPDLC functions over the existing VHF and satellite ACARS (Aircraft
Communications, Addressing and Reporting System) data links. It is designed to allow airlines to
achieve earlier benefits of the CNS/ATM environment.
Note the IFATCA policy: FANS-1/A CPDLC has limitations. Further these shortcomings must
preclude further proliferation of this technology, into states of the world where it is not currently
deployed. Once the Aeronautical Telecommunications Network (ATN) Datalink system is
deployed, use of the FANS-1/A CPDLC shall be replaced by the ATN system and FANS-1/A
systems shall not be accommodated in the ATN, as this would seriously degrade the operational
suitability of the ATN.3
1 CANSO Report on CNS /ATM
2 Except of the Polarregions
3 IFATCA technical manual section 6 / chapter 5
Document prepared by EVP Europe, August 1999 Page 5 of 14
3. GNSS-1
The GNSS 1 will consist of a number of elements. These will include the navigation satellites,
and the ground-based monitoring stations, which, together with communication satellites, will
　
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