Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
− During the vertical ascent and descent, measures include implementing RNAV
departures and using an Optimized Profile Descent (OPD) procedure (previously
known as Continuous Descent Arrival) to optimize the vertical descent of an
aircraft from high altitude to the airport at a near engine idle (as compared to the
step-wise standard approach currently in place). Area Navigation (RNAV) and
Required Navigation Performance (RNP) routes and procedures can allow for
more efficient use of airspace through repeatable/predictable paths, improved
climb and descent profiles, shorter ground tracks, and reduced delays.
− During the horizontal en-route trajectory, domestic reduced vertical separation
minimum (DRVSM) is a recently implemented procedure that provides an
increased probability that pilots will be cleared to their requested optimal cruise
altitude that minimizes fuel use. Other systems such as Advanced Technologies &
Oceanic Procedures (ATOP) and Wide Area Augmentation System (WAAS)
should support more efficient operations by finding more efficient tracks or
altitudes over long oceanic routes and providing precise horizontal and vertical
navigation for landing approaches. ATOP is a satellite-based system that takes
advantage of cockpit digital communications, rather than the voice
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communications used today. Satellite data link communication significantly
reduces the manual workload for controllers, improving their ability to handle
requests from airlines for more efficient routes over the ocean. Automatic
Dependent Surveillance-Broadcast (ADS-B) uses global positioning system (GPS)
and communications satellite signals to more accurately identify and broadcast the
aircraft’s location throughout the flight to safely reduce the separation standards
between aircraft.
Carrier/airport and NAS operations. Some ATM technologies address carrier/airport
as well as NAS operations together. Several systems can improve coordination of
arrival/departure routes to the airport. Departure flow management systems (DFM)
coordinate and automate departure releases, and schedule depeaking can adjust
demand so that the airport operates at or below capacity to reduce congestion.
Integrated terminal weather systems (ITWS) provide better management of arrivals
and departures under varying weather conditions, thus reducing delay.
DRVSM was implemented on a nationwide basis in 2005 (and prior to that, reduced
vertical separation minimum was implemented in some oceanic, foreign and international
airspace). Many of the other ATM measures listed here currently are being applied as part
of the NextGen Implementation Plan (FAA, 2009). 37 Some airports have undertaken
additional initiatives focused on infrastructure and operations, primarily for the purposes
of congestion and delay reduction or air quality improvements. Recent and ongoing
initiatives are described in more detail in the sidebar on page 4-68.
37 The AEO baseline GHG forecasts used in this report assume some improvements in aircraft
efficiency, but it is not made explicit to what extent these result from aircraft improvements
versus system operating improvements. Therefore, it cannot be determined to what extent
initiatives in progress (such as NextGen) are already reflected in these forecasts.
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