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and, if required, given holding instructions. Or, aircraft
are cleared to the airport or to a fix so located that the
handoff will be completed prior to the time the aircraft
reaches the fix. When radar handoffs are used, successive arriving flights may be handed off to approach
control with radar separation in lieu of vertical separation.
After release to approach control, aircraft are vectored
to the final approach course. ATC will occasionally
vector the aircraft across the final approach course for
spacing requirements. The pilot is not expected to turn
inbound on the final approach course unless an
approach clearance has been issued. This clearance will
normally be issued with the final vector for interception of the final approach course, and the vector will
enable the pilot to establish the aircraft on the final
approach course prior to reaching the FAF.
AIR ROUTE TRAFFIC CONTROL CENTER
ARTCCs are approved for and may provide approach
control services to specific airports. The radar systems
used by these Centers do not provide the same precision as an ASR or precision approach radar (PAR) used
by approach control facilities and control towers, and
the update rate is not as fast. Therefore, pilots may be
requested to report established on the final approach
course. Whether aircraft are vectored to the appropriate
final approach course or provide their own navigation
on published routes to it, radar service is automatically
terminated when the landing is completed; or when
instructed to change to advisory frequency at airports
without an operating air traffic control tower,
whichever occurs first. When arriving on an IFR flight
plan at an airport with an operating control tower, the
flight plan will be closed automatically upon landing.
The extent of services provided by approach control
varies greatly from location to location. The majority of
Part 121 operations in the NAS use airports that have
radar service and approach control facilities to assist
in the safe arrival and departure of large numbers of
aircraft. Many airports do not have approach control
facilities. It is important for pilots to understand the
differences between approaches with and without an
approach control facility. For example, consider the
Durango, Colorado, ILS DME RWY 2 and low altitude en route chart excerpt, shown in figure 5-11.
• High or lack of minimum vectoring altitudes
(MVAs) – Considering the fact that most modern
commercial and corporate aircraft are capable of
direct, point-to-point flight, it is increasingly
important for pilots to understand the limitations
of ARTCC capabilities with regard to minimum altitudes. There are many airports that
are below the coverage area of Center radar,
and, therefore, off-route transitions into the
approach environment may require that the
aircraft be flown at a higher altitude than
would be required for an on-route transition.
In the Durango example, an airplane approaching from the northeast on a direct route to the
Durango VOR may be restricted to a minimum
IFR altitude (MIA) of 17,000 feet mean sea
level (MSL) due to unavailability of Center radar
coverage in that area at lower altitudes. An
arrival on V95 from the northeast would be able to
descend to a minimum en route altitude (MEA)
of 12,000 feet, allowing a shallower transition
to the approach environment. An off-route
arrival may necessitate a descent in the published holding pattern over the DRO VOR to
avoid an unstable approach into Durango.
• Lack of approach control terrain advisories –
Flight crews must understand that terrain
clearance cannot be assured by ATC when aircraft are operating at altitudes that are not
served by Center or approach radar. Strict
adherence to published routes and minimum
altitudes is necessary to avoid a controlled
flight into terrain (CFIT) accident. Flight
crews should always familiarize themselves
with terrain features and obstacles depicted on
approach charts prior to initiating the approach.
Approaches outside of radar surveillance require
enhanced awareness of this information.
• Lack of approach control traffic advisories – If
radar service is not available for the approach, the
ability of ATC to give flight crews accurate traffic
advisories is greatly diminished. In some cases,
the common traffic advisory frequency (CTAF)
may be the only tool available to enhance an IFR
flight’s awareness of traffic at the destination
airport. Additionally, ATC will not clear an
IFR flight for an approach until the preceding aircraft on the approach has cancelled
　
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本文鏈接地址：Instrument Procedures Handbook (IPH)儀表程序手冊下(107)