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New TAF Code and 30-hour TAF

The International Civil Aviation Organization (ICAO) makes regular amendments to the standards and recommended practices in Annex 3 to the Convention on International Civil Aviation – Meteorological Service for International Air Navigation. The most significant change (second part of Amendment 74) that has been implemented since 5 November 2008 is the change in TAF code format to facilitate the issuance of 30-hour TAF. Following IATA's requirement, TAF validity at the Hong Kong International Airport (VHHH) has been extended from 24 hours to 30 hours. Detailed changes of TAF format are listed in Table 1.

To assist aviation users and the layman in understanding the TAF in its new format, a webpage on "Automatic Decoding of Aerodrome Forecast (TAF)" has been made available on the AMIDS and on the Observatory's website ( to present the latest TAF in plain language.

Fig.1: Automatic Decoding of TAF.