Decoding TAFs - Visibility MET
When decoding TAFTAF —Terminal Aerodrome Forecasts, it is helpful to cross out anything that does not relate to the matter you are dealing with. Here, anything to do with cloud or wind can be deleted.
Once you have done this, read through the TAFTAF —Terminal Aerodrome Forecast taking careful note of the times to find the visibility. It is measured in metres as a four figure group.
Remember that TEMPO is a temporary change (so after the period it goes back to what it was before) and BECMG is a permanent change (so you can ignore everything before the BECMG if the BECMG has changed something.)
If the time in question falls during a TEMPO (even a PROB30 or PROB40 TEMPO) you must take the worst case scenario - the lowest visibility.
If the time in question falls during a BECMG (becoming) you must again take the worst case scenario - the lowest visibility. If the weather is due to improve, you cannot assume it happened until after the BECMG is finished. If it was due to get worse, assume it got worse immediately when the BECMG started.