Air Traffic Management Concept Baseline Definition - The Boeing ...

8.0 NM
4.0 NM
POPP
PLMN
14.0 NM
30.0 NM
PLWX
4.0 NM
8.0 NM
PWVG
Defined Path
RNP 95% Threshold
Containment Threshold
Figure 5.9 Reduced Separation Between Parallel Oceanic Tracks
In this context, the containment applies to the lateral position of the aircraft. In the future,
the time and vertical components will be added, to provide a four dimensional containment
surface that can be used to support full user-preferred trajectories in four dimensional
flight. In fact, a Required Time of Arrival (RTA) function is already available on several
FMSs, specified as a time at which to reach a waypoint. The first application for this
function could help the crossing of oceanic tracks. This initial RTA function is part of the
FMS performance prediction computation and requires further development to integrate it
with the RNP concept. The ability to design oceanic track procedures based on RNP
containment enables potential economic benefits by allowing more airplanes to fly the
minimum time track along the optimal wind, by reducing fuel burn and fuel reserves.
En route navigation has not benefited to the same extend from the GPS capability and still
uses the basic short-range aid to navigation in the U.S., VOR or VOR/DME. Some new
or recently upgraded airplanes include GPS sensors, typically to provide operational
benefits in other than the en route environment or in areas lacking the VOR/DME
infrastructure. When using the IRS, an approved external navaid must be used to monitor
its performance. Air carrier operators use these navaids, while other operators have
historically used Loran-C and OMEGA. GA airplanes and smaller operators do benefit
from the GPS capability because of its lower acquisition cost.
The VOR/DME navaid forms the basis for the international air navigation system. Over
time it has proven to be safe and adequate, as well as currently representing a large
investment in ground/airborne equipment by both users, governments and institutions
worldwide. At present, almost all commonly traveled U.S. domestic routes are covered
by Jet Routes or Victor Airways supported by the VOR/DME navaid. However, the
VOR/DME system performance is limited so that route width in the domestic phase of
flight varies from 16 to 8 nm at best. The FAA is developing a Wide Area Augmentation
System (WAAS) to increase GPS performance (i.e., primarily integrity and availability, but
also accuracy), as well as a means to phase out land-based navigation aids and reduce
maintenance costs. Introduction of the FMS has freed the airplane from the constraints of
flying fixed routes over navaids and opened up new airspace. FMS-enabled Direct Routes
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