Summary…

 n response to requirements by long haul operations, International Civilian Aviation Organization (ICAO) made provisions for a 30 hour TAF in amendment 74. This code change in Nov 2008 will affect all TAFs. To account for changes to software, publications and training, metrological providers/vendors and users should ensure they are prepared several months ahead of time.  

Intro…  

1.0 With the addition of amendment 74 to Annex 3, the International Civilian Aviation Organization (ICAO) made provisions for a 30 hour TAF. This was in response to requirements by long haul operations to provide better service. The impact to all users and providers will be the change in the current TAF code for all TAFs world wide. More specifically, each change group in a TAF will now have a date. This also applies to states not providing 30 hour TAFs.        

2.0 This information paper is just a reminder to all users that the TAF code will be changing in Nov 2008, less than a year away. Met providers/vendors and users should begin to address whether software will work with the new TAF code, and what publications and training will need to be revised to ensure users are prepared. Below is an  example highlighting the new Date Time Group.     

3.0 The example below is a 30 hour TAF using feet and knots. Further examples and explanations of the 30 hour TAF are also available.

3.1

Typical US TAF using the new 30 hour period

TAF for KCRW (Charleston West Virginia):

 

TAF KCRW 152335Z 1600/1706 13018KT P6SM BKN020

      TEMPO 1608/1612 17025G45KT 1SM TSRA SCT010CB BKN020

      FM170100 15015KT P6SM BKN020

 

Meaning of the forecast:

TAF for Charleston WV issued on the 15th of the month at 2335 UTC valid from the 16th 0000 UTC to the 17th 0600 UTC; surface wind direction 130 degrees; wind speed 18 knots; visibility greater than 6 Statue miles, Sky condition broken at 2000 feet; temporarily between 0800 UTC on the 16th and 1200 UTC on the 16th…surface wind direction 170 degrees; wind speed 25 knots gusting to 45 knots; visibility 1mile in a thunderstorm with moderate rain, scattered cumulonimbus clouds at 1000 feet and broken clouds at 2000 feet; from 0100 UTC on the 17th…the surface wind direction 150 degrees; wind speed 15 knots; visibility greater than 6 Statue miles; and broken clouds at 2000 feet.

 

3.1 The main points to consider are;
  • All TAFs will have to conform to the new Date Time Standard in 5Nov2008
  • Decoding software will likely need to be changed
  • Training publications will need to be changed