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orchestrated and balanced with the resources available.
Current plans for NAS modernization focus on three key
categories:
• Upgrading the infrastructure.
• Providing new safety features.
• Introducing new efficiency-oriented capabilities
into the existing system.
It is crucial that our NAS equipment is protected, as
lost radar, navigation signals, or communications
Figure 1-3. National Airspace
System Plan.
1-4
capabilities can slow the flow of aircraft to a busy city,
which in turn, could cause delays throughout the entire
region, and possibly, the whole country.
The second category for modernization activities
focuses on upgrades concerning safety. Although we
cannot control the weather, it has a big impact on the
NAS. Fog in San Francisco, snow in Denver, thunderstorms in Kansas, wind in Chicago; all of these reduce
the safety and capacity of the NAS. Nevertheless, great
strides are being made in our ability to predict the
weather. Controllers are receiving better information
about winds and storms, and pilots are receiving better
information both before they take off and in flight—all of
which makes flying safer. [Figure 1-4]
Another cornerstone of the FAA’s future is improved navigational information available in the cockpit. The Wide
Area Augmentation System (WAAS) initially became
operational for aviation use on July 10, 2003. It improves
conventional GPS signal accuracy by an order of magnitude, from about 20 meters to 2 meters or less.
Moreover, the local area augmentation system
(LAAS) is being developed to provide even better
accuracy than GPS with WAAS. LAAS will provide
localized service for final approaches in poor weather
conditions at major airports. This additional navigational accuracy will be available in the cockpit and
will be used for other system enhancements. More
information about WAAS and LAAS is contained in
Chapters 5 and 6.
The Automatic Dependent Surveillance (ADS) system, currently being developed by the FAA and several
airlines, enables the aircraft to automatically transmit
its location to various receivers. This broadcast mode,
commonly referred to as ADS-B, is a signal that can
be received by other properly equipped aircraft and
ground based transceivers, which in turn feed the
automation system accurate aircraft position information. This more accurate information will be used to
improve the efficiency of the system—the third category of modernization goals.
Other key efficiency improvements are found in the
deployment of new tools designed to assist the controller. For example, most commercial aircraft
already have equipment to send their GPS positions
automatically to receiver stations over the ocean. This
key enhancement is necessary for all aircraft operating in oceanic airspace and allows more efficient use
of airspace. Another move is toward improving text
and graphical message exchange, which is the ultimate goal of the Controller Pilot Data Link
Communications (CPDLC) Program.
In the en route domain, the Display System
Replacement (DSR), along with the Host/Oceanic
Computer System Replacement (HOCSR) and
Eunomia projects, are the platforms and infrastructure for the future. These provide new displays to the
controllers, upgrade the computers to accept future
tools, and provide modern surveillance and flight
data processing capabilities. For CPDLC to work
effectively, it must be integrated with the en route
controller’s workstation.
RNAV PLANS
Designing routes and airspace to reduce conflicts
between arrival and departure flows can be as simple as
adding extra routes or as comprehensive as a full redesign
in which multiple airports are jointly optimized. New
strategies are in place for taking advantage of existing
structures to departing aircraft through congested transition airspace. In other cases, RNAV procedures are used
to develop new routes that reduce flow complexity by
permitting aircraft to fly optimum routes with minimal
controller intervention. These new routes spread the flow
across the terminal and transition airspace so aircraft can
be separated with optimal lateral distances and altitudes in
and around the terminal area. In some cases, the addition
Figure 1-4. Modernization Activities Provide Improved Weather Information.
1-5
of new routes alone is not sufficient, and redesign of existing routes and flows are required. Benefits are multiplied
when airspace surrounding more than one airport (e.g., in
a metropolitan area) can be jointly optimized.
SYSTEM SAFETY
Although hoping to decrease delays, improve system
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