Updated Date - TAF Coding Change to Occur November 4, 2008

At 5:00 p.m. MST, Tuesday, November 4, 2008, a change in the Terminal Aerodrome Forecast (TAF) will occur that introduces a date/time element to the body of the TAF to include the change groups for all TAFs issued by the National Weather Service.  This change in format is necessary to meet the service requirements as defined by the International Civil Aviation Organization (ICAO) to provide a 30-hour TAF.

A 30-hour TAF is needed to support flight planning requirements for long-haul flights.  With the longer range and cruising time of newer aircraft, the airlines with long-range international flights have found themselves dispatching flights that land beyond the 24-hour TAF valid period.  They are not able to plan fuel or alternates per FAA rules.

For safety purposes, it was decided that all TAFs should adhere to a generic format regardless of the valid period of the TAF. Therefore, the nine TAFs currently distributed by the Riverton NWS office will remain at a 24-hour forecast period while incorporating the format change within the date/time element in the body of the TAF.  This date/time element change will also impact the TAF change groups:  FM (from), TEMPO, and PROB.  Only 32 large hub airports within the United States will actually receive a 30-hour TAF.

An explanation of the 30-hour TAF and a clear example of how to decode the new format can be viewed online. Click here to view more about what the new TAF format will look like in comparison to the current format.  The service change notice from NWS Headquarters outlines the specifics behind this change to a 30-hour format.  Again, this change only effects the formatting of the date/time indicator groups in the TAF.



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