曝光台 注意防骗
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MVA, and they will not be required to descend at more
than 1,000 FPM.
Simultaneous Parallel
ILS Approaches
4,300'
or
Greater
NO TRANSGRESSION ZONE
2,000'
700' or
greater
Figure 5-43. Simultaneous Parallel ILS Approach Criteria.
Simultaneous Close Parallel
ILS Approaches (ILS PRM)
NO TRANSGRESSION ZONE
At Least 3,400'
and Less Than
4,300'
2,000'
700' or
greater
Figure 5-44. Simultaneous Close Parallel ILS Approach (ILS
PRM) Criteria.
5-55
Figure 5-45. St. Louis, Missouri, ILS PRM RWY 11.
5-56
SIMULTANEOUS OFFSET INSTRUMENT
APPROACHES
SOIAs allow simultaneous approaches to two parallel
runways spaced at least 750 feet apart, but less than
3,000 feet. The SOIA procedure utilizes an ILS/PRM
approach to one runway and an offset Localizer-Type
Directional Aid (LDA)/PRM approach with glide
slope to the adjacent runway. The use of PRM technology is also required with these operations; therefore, the approach charts will include procedural
notes such as “Simultaneous approach authorized
with LDA PRM RWY XXX.” San Francisco has the
first published SOIA approach. [Figure 5-46]
The training, procedures, and system requirements for
SOIA ILS/PRM and LDA/PRM approaches are identical with those used for simultaneous close parallel
ILS/PRM approaches until near the LDA/PRM
approach MAP, except where visual acquisition of the
ILS aircraft by the LDA aircraft must be accomplished. If visual acquisition is not accomplished a
missed approach must be executed. A visual segment
for the LDA/PRM approach is established between
the LDA MAP and the runway threshold. Aircraft
transition in visual conditions from the LDA course,
beginning at the LDA MAP, to align with the runway
and can be stabilized by 500 feet above ground level
(AGL) on the extended runway centerline.
The FAA website has additional information about
PRM and SOIA, including instructional videos at:
http://www.faa.gov/education_research/training/prm/
CONVERGING
Another method by which ILS approach capacity can
be increased is through the use of converging
approaches. Converging approaches may be established at airports that have runways with an angle
between 15 and 100 degrees and each runway must
have an ILS. Additionally, separate procedures must be
established for each approach and each approach must
have a MAP at least 3 NM apart with no overlapping of
the protected missed approach airspace. Only straightin approaches are approved for converging ILS procedures. If the runways intersect, the controller must be
able to visually separate intersecting runway traffic.
Approaches to intersecting runways also have higher
minimums with a 700-foot minimum and no less than 2
SM visibility. Pilots are informed of the use of converging ILS approaches by the controller upon initial contact or through ATIS. [Figure 5-47 on page 5-58]
Dallas/Fort Worth International airport is one of the few
airports that makes use of converging ILS approaches
because its runway configuration has multiple parallel
runways and two offset runways. [Figure 5-48 on page
5-58] The approach chart title indicates the use of con-
verging approaches and the notes section highlights
other runways that are authorized for converging
approach procedures.
MICROWAVE LANDING SYSTEM
The MLS is a precision instrument approach alternative to the ILS. It provides azimuth, elevation, and distance information, as well as a back azimuth capable of
providing guidance for missed approach procedures
and departures. In addition to straight-in approaches,
the MLS system can also provide three-dimensional
RNAV type approaches in both computed straight and
curved paths. It was initially designed to replace the
ILS system and it provided inherent flexibility and
broader reception range with the greatest limitation
being the capabilities of the airborne equipment
installed in individual aircraft.
The MLS has multiple advantages including an
increased number of frequencies, compact ground
equipment, and complex approach paths. For a variety
of reasons, particularly the advent of civil use GPS,
MLS installation was deferred, and by 1994 it was officially cancelled by the FAA. Today there are few MLS
installations in the U.S. and currently there are no plans
for further installations. Futhermore, the MLS
equipment required for an MLS approach was not
widely installed in aircraft, whereas most new
aircraft produced today come with GPS systems.
With the limited number of MLS installations
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