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OPERATIONAL TOOLS
Airports are one of the main bottlenecks in the NAS,
responsible for one third of the flight delays. It is widely
accepted that the unconstrained increase in the number
of airports or runways may not wholly alleviate the congestion problem and, in fact, may create more problems
than it solves. The aim of the FAA is to integrate appropriate technologies, in support of the OEP vision, with
the aim of increasing airport throughput.
The airport is a complex system of systems and any
approach to increasing capacity must take this into
account. Numerous recent developments contribute to
the overall solution, but their integration into a system
that focuses on maintaining or increasing safety while
increasing capacity remains a major challenge. The
supporting technologies include new capabilities for
the aircraft and ATC, as well as new strategies for
improving communication between pilots and ATC.
IFR SLOTS
During peak traffic, ATC uses IFR slots to promote a
smooth flow of traffic. This practice began during the
late 1960s, when five of the major airports (LaGuardia
Airport, Ronald Reagan National Airport, John F.
Kennedy International Airport, Newark International
Airport, and Chicago O’Hare International Airport)
were on the verge of saturation due to substantial flight
delays and airport congestion. To combat this, the FAA
in 1968 proposed special air traffic rules to these five
high-density airports (the “high density rule”) that
restricted the number of IFR takeoffs and landings at
each airport during certain hours of the day and provided
for the allocation of “slots” to carriers for each IFR landing or takeoff during a specific 30 or 60-minute period.
A more recent FAA proposal offers an overhaul of the
slot-reservation process for JFK, LaGuardia, and
Reagan National Airport that includes a move to a 72-
hour reservation window and an online slot-reservation
system.
The high density rule has been the focus of much
examination over the last decade since under the
restrictions, new entrants attempting to gain access to
high density airports face difficulties entering the
market. Because slots are necessary at high density
airports, the modification or elimination of the high
density rule could subsequently have an effect on the
value of slots. Scarce slots hold a greater economic
value than slots that are easier to come by.
The current slot restrictions imposed by the high density
rule has kept flight operations well below capacity,
especially with the improvements in air traffic control
technology. However, easing the restrictions imposed
by the high density rule is likely to affect airport oper-
ations. Travel delay time might be affected not only at
the airport that has had the high density restrictions
lifted, but also at surrounding airports that share the
same airspace. On the other hand, easing the restrictions on slots at high density airports should help
facilitate international air travel and help increase the
number of passengers that travel internationally.
Slot controls have become a way of limiting noise,
since it caps the number of takeoffs and landings at
an airport. Easing the restrictions on slots could be
politically difficult since local delegations at the
affected airports might not support such a move. Ways
other than imposing restrictions on slots exist that
could diminish the environmental impacts at airports
and their surrounding areas. Safeguards, such as
requiring the quietest technology available of aircraft
using slots and frequent consultations with local
residents, have been provided to ensure that the
environmental concerns are addressed and solved.
GROUND DELAY PROGRAM
Bad weather often forces the reconfiguration of runways at an airport or mandates the use of IFR arrival
and departure procedures, reducing the number of
flights per hour that are able to takeoff or land at the
affected airport. To accommodate the degraded arrival
capacity at the affected airport, the ATCSCC imposes a
ground delay program (GDP), which allocates a
reduced number of arrival slots to airlines at airports
during time periods when demand exceeds capacity.
The GDP suite of tools is used to keep congestion at an
arrival airport at acceptable levels by issuing ground
delays to aircraft before departure, as ground delays
are less expensive and safer than in-flight holding
delays. The FAA started GDP prototype operations in
January 1998 at two airports and expanded the program
to all commercial airports in the U.S. within nine
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Instrument Procedures Handbook (IPH)仪表程序手册上(33)
