Chris Scott
8th Nov 2008, 13:05
On 5th November, new timings were introduced for the issue and periods of validity of UK Aerodrome TAFs, as those pilots not on leave will already have noticed. [IOM, JER, GCI and ACI seem to have retained their independence.]
The UK Met Office has issued the following two bulletins:
Met Office: Changes to TAF format relating to migration to 30 hour TAF periods (http://www.metoffice.gov.uk/aviation/news/changes/taf.html)
Met Office: Changes to Civilian TAF issue/validity times (http://www.metoffice.gov.uk/aviation/news/changes/civilian.html)
The most obvious change is that the "Long" TAF period has been extended, at the very biggest airports (LHR, LGW, STN & MAN), from 24hrs to 30hrs.
The other protocol that has changed seems to be the introduction of the "FM" (from) group, already widely used in other countries, to supplement the "BECMG" group. The FM group enables a rapid change to be indicated, which ability was lost in the early 1990s, if memory serves, when the formats of UK forecasts and actuals were dumbed-down to conform with many aspects of foreign practice (mainly American).
The third (and innocuous) change is that the timings of the UK Short TAFs have been altered by an hour: e.g., the first new one of the day is no longer from 01-10; it is 00-09 (as always applied in France and Eire, for example).
The changes also mean that, at long-haul airports meriting Long TAFs, the "Short" (9-hour) TAFs will no longer be issued. The Short TAF has been essential until now, because the most recent Long TAF has not been effective until 7 or 8 hours after the time of its issue; and its predecessor is no longer considered valid (and certainly not subject to any necessary amendment). Under the new arrangements, however, the Long (24 & 30-hour) TAFs are issued only 55mins in advance – just like Short (9-hour) TAFs – so, at the start of the period, the most recent thinking of the forecaster is reflected in the TAF.
At a first glance, this looks like a sensible rationalisation. Why would you want a 9-hour TAF covering a part of the day also included in the Long TAF? The snag I see is that the Long TAFs, as before, are only issued every 6hrs, whereas the Short TAFs are still issued every 3hrs. Will the Long TAF be routinely reviewed, 3 hours after issue, with a view to possible amendment? Will that, or any ad-hoc amendments, be easily and reliably available to crews abroad?
The possible anomaly which concerns me is that airports meriting a Long TAF may now be getting fewer updates (covering the initial 9-hour period) than previously. Curiously, this does not seem to apply to smaller aerodromes retaining the Short TAF only. So this applies mainly to short-haul operations at airports of medium size and above; including most of the airports that operate scheduled flights. On the plus side, it is to be welcomed that most of these scheduled airports are now provided with forecasts suitable for long-haul operations.
The UK Met Office has issued the following two bulletins:
Met Office: Changes to TAF format relating to migration to 30 hour TAF periods (http://www.metoffice.gov.uk/aviation/news/changes/taf.html)
Met Office: Changes to Civilian TAF issue/validity times (http://www.metoffice.gov.uk/aviation/news/changes/civilian.html)
The most obvious change is that the "Long" TAF period has been extended, at the very biggest airports (LHR, LGW, STN & MAN), from 24hrs to 30hrs.
The other protocol that has changed seems to be the introduction of the "FM" (from) group, already widely used in other countries, to supplement the "BECMG" group. The FM group enables a rapid change to be indicated, which ability was lost in the early 1990s, if memory serves, when the formats of UK forecasts and actuals were dumbed-down to conform with many aspects of foreign practice (mainly American).
The third (and innocuous) change is that the timings of the UK Short TAFs have been altered by an hour: e.g., the first new one of the day is no longer from 01-10; it is 00-09 (as always applied in France and Eire, for example).
The changes also mean that, at long-haul airports meriting Long TAFs, the "Short" (9-hour) TAFs will no longer be issued. The Short TAF has been essential until now, because the most recent Long TAF has not been effective until 7 or 8 hours after the time of its issue; and its predecessor is no longer considered valid (and certainly not subject to any necessary amendment). Under the new arrangements, however, the Long (24 & 30-hour) TAFs are issued only 55mins in advance – just like Short (9-hour) TAFs – so, at the start of the period, the most recent thinking of the forecaster is reflected in the TAF.
At a first glance, this looks like a sensible rationalisation. Why would you want a 9-hour TAF covering a part of the day also included in the Long TAF? The snag I see is that the Long TAFs, as before, are only issued every 6hrs, whereas the Short TAFs are still issued every 3hrs. Will the Long TAF be routinely reviewed, 3 hours after issue, with a view to possible amendment? Will that, or any ad-hoc amendments, be easily and reliably available to crews abroad?
The possible anomaly which concerns me is that airports meriting a Long TAF may now be getting fewer updates (covering the initial 9-hour period) than previously. Curiously, this does not seem to apply to smaller aerodromes retaining the Short TAF only. So this applies mainly to short-haul operations at airports of medium size and above; including most of the airports that operate scheduled flights. On the plus side, it is to be welcomed that most of these scheduled airports are now provided with forecasts suitable for long-haul operations.