AIM
8/15/19
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52
Meteorology
gust front detection, storm growth and decay,
microburst prediction, and turbulence detection.
(c)
TDWR also provides a geographical
situation display (GSD) for supervisors and traffic
management specialists for planning purposes. The
GSD displays (in color) 6 levels of weather
(precipitation), gust fronts and predicted storm
movement(s). This data is used by the tower
supervisor(s), traffic management specialists and
controllers to plan for runway changes and
arrival/departure route changes in order to both
reduce aircraft delays and increase airport capacity.
4. Weather System Processor (WSP).
(a)
The WSP provides the controller, supervi-
sor, traffic management specialist, and ultimately the
pilot, with the same products as the terminal doppler
weather radar (TDWR) at a fraction of the cost of a
TDWR. This is accomplished by utilizing new
technologies to access the weather channel capabili-
ties of the existing ASR
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9 radar located on or near the
airport, thus eliminating the requirements for a
separate radar location, land acquisition, support
facilities and the associated communication landlines
and expenses.
(b)
The WSP utilizes the same RBDT display
as the TDWR and LLWAS, and, just like TDWR, also
has a GSD for planning purposes by supervisors,
traffic management specialists and controllers. The
WSP GSD emulates the TDWR display, i.e., it also
depicts 6 levels of precipitation, gust fronts and
predicted storm movement, and like the TDWR GSD,
is used to plan for runway changes and arrival/depar-
ture route changes in order to reduce aircraft delays
and to increase airport capacity.
(c)
This system is currently under develop-
ment and is operating in a developmental test status
at the Albuquerque, New Mexico, airport. When
fielded, the WSP is expected to be installed at
34 airports across the nation, substantially increasing
the safety of the American flying public.
5. Operational aspects of LLWAS, TDWR
and WSP.
To demonstrate how this data is used by both the
controller and the pilot, 3 ribbon display examples
and their explanations are presented:
(a) MICROBURST ALERTS
EXAMPLE
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This is what the controller sees on his/her ribbon display
in the tower cab.
27A MBA 35K
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2MF 250 20
NOTE
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(See FIG 7
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1
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17 to see how the TDWR/WSP determines
the microburst location).
This is what the controller will say when issuing the
alert.
PHRASEOLOGY
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RUNWAY 27 ARRIVAL, MICROBURST ALERT, 35 KT
LOSS 2 MILE FINAL, THRESHOLD WIND 250 AT 20.
In plain language, the controller is telling the pilot
that on approach to runway 27, there is a microburst
alert on the approach lane to the runway, and to
anticipate or expect a 35 knot loss of airspeed at
approximately 2 miles out on final approach (where
it will first encounter the phenomena). With that
information, the aircrew is forewarned, and should be
prepared to apply wind shear/microburst escape
procedures should they decide to continue the
approach. Additionally, the surface winds at the
airport for landing runway 27 are reported as
250 degrees at 20 knots.
NOTE
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Threshold wind is at pilot’s request or as deemed
appropriate by the controller.
REFERENCE
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FAA Order JO 7110.65, Paragraph 3
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8b2(a), Air Traffic Control, Low
Level Wind Shear/Microburst Advisories