Aeronautical Information Manual (AIM), page 498

Index   497 -- Page 498 -- 499

AIM      CHG 2                                                                                             3/15/07

    6. The Terminal Weather Information for               within 30 NM surrounding the terminal area, and
Pilots System (TWIP).                                     expected weather that will impact airport operations.
                                                          During inclement weather, i.e., whenever a predeter-
       (a) With the increase in the quantity and
                                                          mined level of precipitation or wind shear is detected
quality of terminal weather information available
                                                          within 15 miles of the terminal area, TWIP products
through TDWR, the next step is to provide this
                                                          are updated once each minute for text messages and
information directly to pilots rather than relying on
                                                          once every five minutes for character graphic
voice communications from ATC. The National
                                                          messages. During good weather (below the predeter-
Airspace System has long been in need of a means of
                                                          mined precipitation or wind shear parameters) each
delivering terminal weather information to the
                                                          message is updated every 10 minutes. These products
cockpit more efficiently in terms of both speed and
                                                          are intended to improve the situational awareness of
accuracy to enhance pilot awareness of weather
                                                          the pilot/flight crew, and to aid in flight planning prior
hazards and reduce air traffic controller workload.
                                                          to arriving or departing the terminal area. It is
With the TWIP capability, terminal weather
                                                          important to understand that, in the context of TWIP,
information, both alphanumerically and graphically,
                                                          the predetermined levels for inclement versus good
is now available directly to the cockpit at 43 airports
                                                          weather has nothing to do with the criteria for
in the U.S. NAS. (See FIG 7-1-18.)
                                                          VFR/MVFR/IFR/LIFR; it only deals with precipita-
FIG 7-1-18 tion, wind shears and microbursts. TWIP Image of Convective Weather TBL 7-1-11 at MCO International 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 (b) TWIP products are generated using Dallas Love Field Airport KDAL weather data from the TDWR or the Integrated James M. Cox Intl Airport KDAY Terminal Weather System (ITWS) testbed. TWIP Ronald Reagan Washington National Air- KDCA products are generated and stored in the form of text port and character graphic messages. Software has been developed to allow TDWR or ITWS to format the Denver Intl Airport KDEN data and send the TWIP products to a database Dallas-Fort Worth Intl Airport KDFW resident at Aeronautical Radio, Inc. (ARINC). These Detroit Metro Wayne County Airport KDTW products can then be accessed by pilots using the Newark Liberty Intl Airport KEWR ARINC Aircraft Communications Addressing and Reporting System (ACARS) data link services. Fort Lauderdale-Hollywood Intl Airport KFLL Airline dispatchers can also access this database and William P. Hobby Airport KHOU send messages to specific aircraft whenever wind Washington Dulles Intl Airport KIAD shear activity begins or ends at an airport. George Bush Intercontinental Airport KIAH (c) TWIP products include descriptions and Wichita Mid-Continent Airport KICT character graphics of microburst alerts, wind shear alerts, significant precipitation, convective activity Indianapolis Intl Airport KIND 7-1-54 Meteorology

Page 498 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

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