AIM

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7−1−54

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−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

−

This is what the controller sees on his/her ribbon display
in the tower cab.

27A MBA 35K− 2MF 250 20

NOTE

−

(See FIG 7

−1−19 to see how the TDWR/WSP determines

the microburst location).

This is what the controller will say when issuing the

alert.

PHRASEOLOGY

−

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

−

Threshold wind is at pilot’s request or as deemed
appropriate by the controller.

REFERENCE

−

FAA Order JO 7110.65, Air Traffic Control, Low Level Wind
Shear/Microburst Advisories, Paragraph 3

−1−8b2(a).