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8.2.3. Improvements to ATM System
8.2.3.1. Introduction
The description, goals, and objectives of an improved global air navigation
infrastructure emanate from the concept known as communications, navigation,
and surveillance/air traffic management (CNS/ATM) systems. CNS/ATM was formally
endorsed by the worldwide civil aviation community at the Tenth Air Navigation
Conference in Montreal in 1991 (ICAO, 1991).
The primary goal of an integrated ATM system is to enable aircraft operators
to meet planned times of departure and arrival and adhere to preferred flight
profiles with minimum constraints and no compromise on safety. Therefore, although
an integrated, global ATM system grew out of a need to meet growing demand,
the ultimate effect will be enhanced operations and improved efficiency, primarily
through less fuel burn for a given level of demand. ATM systems will therefore
be developed and organized to overcome shortcomings discussed in this chapter
and to accommodate future growth to offer the best possible service to all airspace
users and to provide adequate economic benefits to the civil aviation community,
with due regard for environmental concerns.
CNS/ATM has been defined as a system employing digital technologies, including
satellite systems together with various levels of automation, applied in support
of a seamless global air traffic management system. The main elements of CNS/ATM
systems are described in detail in the ICAO Global Air Navigation Plan for CNS/ATM
Systems (ICAO, 1998a). CNS/ATM systems will use very high frequency (VHF) and
high frequency (HF) communication channels to transmit digital data between
aircraft and between aircraft and ground stations. Satellite data and voice
communications capable of global coverage are also being introduced. Improvements
in navigation include progressive introduction of area navigation (RNAV) capabilities
based on a global navigation satellite system (GNSS). Improvements in surveillance
techniques will allow aircraft to automatically transmit their positions using
data link technology.
It is generally agreed that these newer technologies will optimize the worldwide
route structure. Planners will be less confined by the location of ground aids
and more direct tracks will be used, allowing substantial savings in fuel. Ultimately,
rigid route structures will be gradually eliminated or redesigned at a number
of critical intersections. This flexibility has the potential to relieve congestion
in very high density traffic areas.
8.2.3.2. Airport Operations and Capacity
In some regions, the increasing gap between traffic demand and capacity provided
by the physical infrastructure at many key airports is a critical limiting factor.
CNS/ATM systems can contribute to increasing capacity. Sophisticated automation
and digital data links will help to make maximum use of available capacity and
meet throughput requirements by improving the identification and predicted movement
of aircraft and vehicles in the airport movement area. Additionally, increasing
levels of collaboration and information-sharing between aircraft operators and
ATM providers will create a more realistic picture of airport departure and
arrival demand, allowing operators to make dynamic scheduling and flight planning
decisions based on the ATM situation at any given time.
8.2.3.3. TMA Operations and Capacity
Enhanced instrument approach techniques will improve the flexibility of approach
operations, thereby reducing noise and emissions levels. Parallel runways spaced
as closely as 760 m or less are expected to routinely accommodate independent
instrument flight rule (IFR) approaches based on high-data-rate secondary surveillance
radars, data link technologies, improved cockpit and air traffic controller
displays, and advanced automation. This technology will provide capacity increases
in instrument meteorological conditions (IMC) at locations with such closely
spaced runways. Also, automation tools will assist air traffic managers in establishing
efficient flows of approaching aircraft for parallel and converging runway configurations.
8.2.3.4. En Route Operations
The flow management process will monitor capacity resources and demand at airports
and in terminal and en route airspace and will implement strategies, where required,
to protect ATC from overloads and to provide an optimal flow of traffic by making
best use of available airspace capacity. Clearances involving position and time,
using an ATM data link interface with flight management computers, will be principal
tools in assuring that ATM constraints are met with minimum deviation from user-preferred
trajectories. The ability to predict optimum trajectory and monitor conformance
of aircraft along these trajectories will allow the most efficient flight profiles
and routes-resulting in an increase in overall efficiency, reductions in average
fuel consumption per flight, and, consequently, reduced emissions levels for
a given demand.
8.2.3.5. Oceanic Operations
Future oceanic ATM operations will make extensive use of data link technologies,
GNSS, HF and satellite-based digital communications, aviation weather system
improvements, and collaborative decisionmaking techniques. Planned implementation
of reduced longitudinal and lateral separation minima and reduced vertical separation
(RVSM), along with more flexible handling of flights, is expected to lead to
fuel savings. Implementation of RVSM above 8,850 m in the North Atlantic region
has already resulted in increased capacity and reduced fuel consumption.
8.2.3.6. Meteorological Information
More timely weather information will be available as a result of two developments:
Implementation of the final phase of the world area forecast system (WAFS),
which uses direct satellite communications to deliver information to states,
and increasing use of air-to-ground data link communications to uplink operational
meteorological information. With these developments, the restrictions placed
on the exchange of operational meteorological information are gradually being
lifted.
With regard to the presentation of meteorological information, the increasing
use of graphical information will be made possible by the introduction of air-to-ground
data links.
With regard to the accuracy of meteorological information, introduction of
the final phase of WAFS will increase the quality of meteorological information
provided. However, future improvements in accuracy will depend significantly
on the availability of frequent automatic dependent surveillance (ADS) reports,
which include a meteorological information data block. Improved observing and
forecasting techniques for volcanic ash and clear-air turbulence will eliminate
overprediction of airspace affected by these phenomena, which can restrict the
use of airspace. In the terminal area, integrated terminal weather systems will
improve the accuracy of information provided regarding hazardous weather phenomena.
Furthermore, real-time wind models run by ATC computers, based on ADS reports
obtained during the climb-out phase, will be used to monitor the evolution of
the wind field, which is required by ATC for sequencing of approaching aircraft.
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