afi met bulletins exchange (ambex) handbook - ICAO

AMBEX HANDBOOK 7th Ed. 22/58
6.4.1.1 24- and 30-hour TAFs should be issued at intervals of six hours, with the period of validity
beginning at one of the main synoptic hours (00, 06, 12, 18 UTC), as shown in the table below.
Synoptic hours
(UTC)
24-hour TAF
Period of
Filing Time
validity
30-hour TAF
Period of
Filing Time
validity
00 00-24 22 (-1)* 00-06 (+1) 22 (-1)*
06 06-06 04 06-12 (+1) 04
12 12-12 10 12-18 (+1) 10
18 18-18 16 18-24 (+1) 16
*Note: “-1” indicates the previous day and “+1” indicates the next day
6.4.1.2 All TAFs in a AMBEX TAF bulletin should have a common period of validity. It is not
allowed to mix “long” and “short” TAFs in one bulletin.
6.4.2 Each TAF message in a TAF bulletin should start with the code word TAF followed by the
ICAO location indicator (CCCC) of the aerodrome and the date/time group (YYGGggZ), indicating the
official time of issuance. Corrected TAF messages, should start with TAF COR. Amended forecasts
should start with TAF AMD.
6.4.3 The use of the BBB group in the WMO heading for delayed, corrected, or amended TAFs
is described in Appendix C.
6.4.4 The following is an outline of the format to be applied by a AMBEX centre in preparing a
TAF bulletin, containing “long” TAFs (24 or 30 hour):
Parts of Message AMBEX FT Bulletin
AFTN header
Priority Indicator and Address GG YBBBYPYX
Date and Time of filing and Originator 271104 ZBBBYPYX
WMO Abbreviated Heading FTCI31 ZBBB 271100
TAF messages TAF ZBAA 271000Z 2712/2812..…=
TAF ZBTJ 271000Z 2712/2818…….=
AFTN Normal Ending NNNN…..
6.4.5 A missing TAF in a non TAF bulletin should be indicated with “NIL”, as shown in the
following example:
TAF VTBD 281000Z NIL=
6.4.6 A cancelled TAF in a TAF bulletin should be indicated with “CNL”, as shown in the
following example:
TAF VTBD 281000Z 2812/2912 CNL=