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type of NAVAID provides an approach course between
3 and 6 degrees, making it similar in accuracy to a
localizer, but remember that the LDA is not as closely
aligned with the runway and it does not offer a navigable back course. Currently there are less than 30 LDA
installations in the U.S., and as a result, most pilots are
not familiar with this type of instrument approach.
[Figure 5-58]
SIMPLIFIED DIRECTIONAL FACILITY
The SDF is another instrument approach system that is
not as accurate as the LOC approach facilities. Like the
LOC type approaches, the SDF is an alternative
approach that may be installed at an airport for a variety of reasons, including terrain. The final approach
Figure 5-57. Baton Rouge Metro/Ryan (KBTR), Baton Rouge, Louisiana, LOC BC RWY 4L.
5-67
Figure 5-58. Hartford-Brainard (KHFD), Hartford, Connecticut, LDA RWY 2.
5-68
course width of an SDF system is set at either 6 or 12
degrees. The SDF is a nonprecision approach since it
only provides lateral guidance to the runway.
For straight-in SDF approaches, the angle of convergence for the final approach course and the extended
runway centerline is 30 degrees or less, and if the
angle of convergence is beyond 30 degrees, the SDF
will only have circling minimums. An SDF approach
is provided a minimum of 250 feet obstacle clearance
for straight-in approaches while in the final approach
area, which is an area defined for a 6 degrees course:
1,000 feet at or abeam the runway threshold expanding to 19,228 feet 10 NM from the threshold. The
same final approach area for a 12 degrees course is
larger. This type of approach is also designed with a
maximum descent gradient of 400 feet per NM, unless
circling only minimums are authorized. [Figure 5-59]
Figure 5-59. Newark-Heath (KVTA), Newark, Ohio, SDF RWY 9.
6-1
In the next ten years, exciting new technologies will be
implemented to help ease air traffic congestion, add to
system capacity, and enhance safety. Some of these
changes will be invisible to pilots and will be made
seamlessly. Others will entail changing some old habits
and learning new procedures. New aircraft equipment
will bring powerful new capabilities, but will require
training and practice to master.
FLEET IMPROVEMENT
Airlines and other operators will continue trying to find
more efficient ways to use the National Airspace System
(NAS). More and more users are working with federal
agencies to write new policies and develop exchanges of
real-time flight information, all in the interest of improving their service as well as their bottom lines. As new
business strategies emerge, there also will be changes in
the aircraft fleet. For example, as regional jets continue to
increase in popularity, they have significant potential to
reduce traffic at major airports as well as on the most
crowded airways. Providing service along underused area
navigation (RNAV) routes directly between smaller city
pairs, they can bypass congested hubs and avoid airborne
choke points. The number of regional jets is forecast to
increase by more than 80 percent in the next decade.
Compared to the turboprop airplanes they will replace,
RJs fly at similar speeds and altitudes as larger jets, so
they mix into traffic
streams more smoothly,
making en route traffic
management easier for
controllers. [Figure 6-1]
At the other end of
the spectrum, larger
airplanes capable of
carrying over 500
passengers are now
flying. These “superjumbos” have the
potential to reduce
airway and terminal
congestion by transporting more people
in fewer airplanes.
This ability is especially valuable at major hubs, where the
number of flight operations exceeds capacity at certain
times of day. On the other hand, some of these airplanes
have a double-deck configuration that might require
extensive changes to terminals so that large numbers of
passengers can board and deplane quickly and safely.
Their size may require increased separation of taxiways
and hold lines from runways due to increased wingspans
and tail heights. Their weight also may require stronger
runways and taxiways, as well as increased separation
requirements for wake turbulence. [Figure 6-2]
Other innovative airplanes include the turbofan-powered
very light jets (VLJs), which are relatively small turbo-
Figure 6-1. Regional Jets.
Figure 6-2. Superjumbo Airplanes.
6-2
fan-powered aircraft with 6 to 8 seats, with cruising
speeds between 300 and 500 knots, and with a range of
around 1,000 nautical miles (NMs). [Figure 6-3] If initial orders are an accurate indicator of their popularity,
　
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