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AIM

10/12/17

7−1−56

Meteorology

6. The Terminal Weather Information for

Pilots System (TWIP).

(a) With the increase in the quantity and

quality of terminal weather information available

through TDWR, the next step is to provide this

information directly to pilots rather than relying on

voice communications from ATC. The National

Airspace System has long been in need of a means of

delivering terminal weather information to the

cockpit more efficiently in terms of both speed and

accuracy to enhance pilot awareness of weather

hazards and reduce air traffic controller workload.

With the TWIP capability, terminal weather

information, both alphanumerically and graphically,

is now available directly to the cockpit at 43 airports

in the U.S. NAS. (See FIG 7−1−20.)

FIG 7−1−20

TWIP Image of Convective Weather 

at MCO International

(b) TWIP products are generated using

weather data from the TDWR or the Integrated

Terminal Weather System (ITWS) testbed. TWIP

products are generated and stored in the form of text

and character graphic messages. Software has been

developed to allow TDWR or ITWS to format the

data and send the TWIP products to a database

resident at Aeronautical Radio, Inc. (ARINC). These

products can then be accessed by pilots using the

ARINC Aircraft Communications Addressing and

Reporting System (ACARS) data link services.

Airline dispatchers can also access this database and

send messages to specific aircraft whenever wind

shear activity begins or ends at an airport.

(c) TWIP products include descriptions and

character graphics of microburst alerts, wind shear

alerts, significant precipitation, convective activity

within 30 NM surrounding the terminal area, and

expected weather that will impact airport operations.

During inclement weather, i.e., whenever a predeter-

mined level of precipitation or wind shear is detected

within 15 miles of the terminal area, TWIP products

are updated once each minute for text messages and

once every five minutes for character graphic

messages. During good weather (below the predeter-

mined precipitation or wind shear parameters) each

message is updated every 10 minutes. These products

are intended to improve the situational awareness of

the pilot/flight crew, and to aid in flight planning prior

to arriving or departing the terminal area. It is

important to understand that, in the context of TWIP,

the predetermined levels for inclement versus good

weather has nothing to do with the criteria for

VFR/MVFR/IFR/LIFR; it only deals with precipita-

tion, wind shears and microbursts.

TBL 7−1−11

TWIP−Equipped Airports

Airport

Identifier

Andrews AFB, MD

KADW

Hartsfield−Jackson Atlanta Intl Airport

KATL

Nashville Intl Airport

KBNA

Logan Intl Airport

KBOS

Baltimore/Washington Intl Airport

KBWI

Hopkins Intl Airport

KCLE

Charlotte/Douglas Intl Airport

KCLT

Port Columbus Intl Airport

KCMH

Cincinnati/Northern Kentucky Intl Airport KCVG
Dallas Love Field Airport

KDAL

James M. Cox Intl Airport

KDAY

Ronald Reagan Washington National Air-

port

KDCA

Denver Intl Airport

KDEN

Dallas−Fort Worth Intl Airport

KDFW

Detroit Metro Wayne County Airport

KDTW

Newark Liberty Intl Airport

KEWR

Fort Lauderdale−Hollywood Intl Airport

KFLL

William P. Hobby Airport

KHOU

Washington Dulles Intl Airport

KIAD

George Bush Intercontinental Airport

KIAH

Wichita Mid−Continent Airport

KICT

Indianapolis Intl Airport

KIND