USING TAFS (Terminal Aerodrome Forecasts)

USING TAFs The purpose of this presentation is to explain: What a TAF is; What a TAF is; How to register with the Met Office and access TAFs; How to register with the Met Office and access TAFs; How to understand i.e. “decode” TAFs. How to understand i.e. “decode” TAFs.

WHAT IS A TAF ? A TAF is a Terminal Aerodrome Forecast (sometimes referred to as a Terminal Area Forecast. A TAF is a weather forecast specific to the locality of an aerodrome so that a pilot intending to travel there can acquaint himself with the likely weather conditions relevant to an approach and landing.

HOW DO WE REGISTER FOR ACCESS TO TAFs ? TAF are made available by the Met Office and before you can access them (and other weather information for pilots) you need to register as a user. Registration is a simple procedure and “free”, simply go to the following website:

If you are using your own PC you can register with the Met Office at:

Simply fill in a few details, name, address, etc.,select a username and password and you are done. Don't worry its FREE !

Once registered or if you are using the club PC you can then logon at:

Now all you need to do is enter the username and password which you have registered and off you go

Click on the Launch button and it takes you the Home Page

You can choose between a number of options, the most useful being Forms F214 / F215 and the TAFs. For the TAFS click here

For TAFs in the our area click here

Here is the forecast for Bristol Airport

and this is the TAF which we will “decode”

Understanding the TAF Code TAFs are written in a standard format with the various data elements laid out in a standard sequence. Some TAFs (the short ones) comprise a single forecast covering the whole of the specified forecast period. The more complex TAFs may have additional forecasts for specific periods within the overall forecast period. The elements of the TAF are as follows:

Understanding the TAF Code The first part of the TAF is always in the same format and sequence: The aerodrome ident e.g. EGGD; The aerodrome ident e.g. EGGD; The date and time of issue of the forecast e.g Z; The date and time of issue of the forecast e.g Z; The period covered by the forecast e.g. 1506/1606; The period covered by the forecast e.g. 1506/1606; The wind direction and speed e.g KT; The wind direction and speed e.g KT; The visibility in metres e.g. 3000; The visibility in metres e.g. 3000; The weather (essentially any precipitation) e.g. BR; The weather (essentially any precipitation) e.g. BR; The cloud cover and its base e.g. BKN006. The cloud cover and its base e.g. BKN006.

Understanding the TAF Code For ease of explanation, decoding a TAF is best done with the help of a table covering the various elements we can expect to find in the TAF.

First, we copy the TAF code into this box

This is the aerodrome ident for Bristol

Enter this here

This is the date and time of the forecast i.e. “Issued on the 15 th at 0458 hrs (zulu).

Enter this here

This is the date and time period of the forecast i.e. “From 0600 hrs on the 15 th to 0600 hrs on the 16th

Enter this here

and here

This is tells us about the wind, which in this case decodes as “Direction 040 degrees, and speed 10 kts

Enter this here

This is the visibility – 3000 metres,

Enter this here

This code tells us about the weather, more specifically the precipitation, in this case “mist”.

Enter this here

This is tells us about the cloud which in this case decodes as “Broken cloud (5 -7 oktas), cloud base 600' “

Enter this here

Understanding the TAF Code We have now decoded the main section of the forecast. Anything that follows will be a change from the initial / overall forecast. These extra sections which usually start with BECMG, PROB or TEMPO, will state the time period and perhaps the probability of the change and may cover only one or some of the forecast elements rather than them all. So let's continue the process..

This part tells us of a possible change, namely that with a probability of 40% and between 0600 hrs and 0900 hrs on the 15 th there could be rain and broken cloud with cloudbase at 300'

Enter all this along this line

This part tells us of a change that will occur between 0900 hrs and 1200 hrs on the 15 th namely that the wind will veer to 070 degrees and 15 kts gusting 25 kts, the visibility will increase to 7000 metres and the cloud will disperse to scattered (3-4 oktas) with cloudbase at 1500'.

Enter this along this line

This tells us that with a probability of 30% and between 1200 hrs and 1900 hrs on the 15 th the visibility will improve to at least 9999 metres

Enter this along this line

This tells us that between 1200 hrs on the 15 th and 0200 hrs on the 16 th there will be short periods of showers of rain

Enter this along this line

This tells us that with a 30% probability and between 1400 hrs and 1900 hrs on the 15 th there will be short periods when the visibility will drop to 3000 metres and there will be heavy rain showers and thundery rain showers

Enter this along this line

And finally between 1800 hrs and 2100 hrs on the 15 th the wind will veer to 080 degrees 12 kts

Enter this along this line

Understanding the TAF Code We have now decoded the follow-on sections of the forecast which indicate changes from the initial / overall forecast. An explanation of all the codes used in TAFs is included on the Met Office website at: For convenience the more commonly used codes are set out on the next slide.

VISIBILITY BR – Mist FG – Fog HZ – HazePRECIPITATION DZ – Drizzle GR – Hail RA – Rain SN – Snow TS - ThunderstormCLOUD SKC – Sky Clear FEW – Few (1-2 oktas) SCT – Scattered (3-4 oktas) BKN – Broken(5-7 oktas)TIMING BCMG – Becoming TEMPO - Temporary periods (less than 1 hour) PROB - Probability percentage FM – From AT – At TL - Until

Understanding the TAF Code Finally, if all this proves to be too difficult, you can still use the TAFs but with an “automatic” decoder. Simply go to Skystefs page at: enter the code for the aerodrome, tick the relevant boxes and “Hey presto” you have the information.

To Conclude So what have we achieved ? We know that a TAF is a Terminal Aerodrome Forecast; We know that a TAF is a Terminal Aerodrome Forecast; We know how to register and gain access to TAFs at the Met Office website; We know how to register and gain access to TAFs at the Met Office website; We know that the weather forecast information in a TAF follows a strict sequence namely; wind direction and strength, visibility, weather (precipitiation) and then cloud cover and cloud base. We know that the weather forecast information in a TAF follows a strict sequence namely; wind direction and strength, visibility, weather (precipitiation) and then cloud cover and cloud base.

That's all for now folks.....