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around 4.3 percent per year. Commercial aviation is
expected to exceed one billion passengers by 2015. The
system is nearing the point of saturation, with limited
ability to grow unless major changes are brought about.
Adding to the growth challenge, users of the NAS cover a
wide spectrum in pilot skill and experience, aircraft types,
and air traffic service demands, creating a challenge to the
NAS to provide a variety of services that accommodate all
types of traffic. NAS users range from professional airline,
commuter, and corporate pilots to single-engine piston
pilots, as well as owner-operators of personal jets to military
jet fighter trainees.
AIRLINES
Though commercial air carrier aircraft traditionally
make up less than 5 percent of the civil aviation fleet,
they account for about 30 percent of the instrument
operations flown in civil aviation. Commercial air carriers are the most homogenous category of airspace users,
although there are some differences between U.S. trunk
carriers (major airlines)
and regional airlines
(commuters) in terms
of demand for ATC
services. Generally,
U.S. carriers operate
large, high performance airplanes that
cruise at altitudes
above 18,000 feet.
Conducted exclusively
under IFR, airline
flights follow established schedules and
operate in and out of
larger and betterequipped airports. In
terminal areas, however, they share airspace
and facilities with all
types of traffic and must
compete for airport
access with other users.
Airline pilots are highly
proficient and thoroughly familiar with the rules and procedures under which they must operate.
Some airlines are looking toward the use of larger
aircraft, with the potential to reduce airway and terminal congestion by transporting more people in
fewer aircraft. This is especially valuable at major
hub airports, where the number of operations
exceeds capacity at certain times of day. On the
other hand, the proliferation of larger aircraft also
requires changes to terminals (e.g., double-decker
jetways and better passenger throughput), rethinking
of rescue and fire-fighting strategies, taxiway fillet
changes, and perhaps stronger runways and
taxiways.
Commuter airlines also follow established schedules
and are flown by professional pilots. Commuters
characteristically operate smaller and lower performance aircraft in airspace that must often be shared by
general aviation (GA) aircraft, including visual flight
rules (VFR) traffic. As commuter operations have
grown in volume, they have created extra demands on
the airport and ATC systems. At one end, they use hub
airports along with other commercial carriers, which
contributes to growing congestion at major air traffic
hubs. IFR-equipped and operating under IFR like
other air carriers, commuter aircraft cannot be used to
full advantage unless the airport at the other end of
the flight, typically a small community airport, also is
capable of IFR operation. Thus, the growth of commuter air service has created pressure for additional
SEA
PDX
SFO
SJC
LAX
SAN
LAS
SLC
PHX
DEN
DFW
IAH
MCI
STL
MEM
BNA
IND
ATL
TPA
MCO
FLL
MIA
CLT
RDU
CVG
IAD
DCA
BWI
CLE
DTW
PIT
TEB
EWR
PHL
LGA
JFK
BOS
ORD
MDW
MSP
Figure 1-7. A real-time Airport Status page displayed on the ATCSCC Web site
(www.fly.faa.gov/flyfaa/usmap.jsp) provides general airport condition status. Though not flight
specific, it portrays current general airport trouble spots. Green indicates less than five-minute
delays. Yellow means departures and arrivals are experiencing delays of 16 to 45 minutes. Traffic
destined to orange locations is being delayed at the departure point. Red airports are experiencing taxi or airborne holding delays greater than 45 minutes. Blue indicates closed airports.
1-9
instrument approach procedures and control facilities
at smaller airports. A growing trend among the major
airlines is the proliferation of regional jets (RJs). RJs
are replacing turboprop aircraft and they are welcomed by some observers as saviors of high-quality
jet aircraft service to small communities. RJs are
likely to be a regular feature of the airline industry for
a long time because passengers and airlines overwhelmingly prefer RJs to turboprop service. From the
passengers’ perspective, they are far more comfortable; and from the airlines’ point of view, they are
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Instrument Procedures Handbook (IPH)仪表程序手册上(18)
