FAA Aircraft Dispatcher (ADX)MeteorologyMedium
A TAF for a destination airport contains the group 'BECMG 1416 3SM BR'. How should a dispatcher interpret this forecast group?
- AThere is a 30 percent probability of 3SM visibility in mist during the period
- BVisibility will remain at or below 3SM continuously throughout the entire 1400Z–1600Z period only
- CA gradual change to 3SM visibility in mist is expected sometime between 1400Z and 1600Z, becoming the prevailing condition thereafter
- DVisibility will temporarily drop to 3SM in mist between 1400Z and 1600Z, then return to prior conditions
Show answer & explanationAnswer & explanation
Correct answer: C. A gradual change to 3SM visibility in mist is expected sometime between 1400Z and 1600Z, becoming the prevailing condition thereafter
BECMG (becoming) indicates a gradual, permanent change in conditions expected to occur within the stated time window, with the new condition becoming the prevailing forecast thereafter, unlike TEMPO which indicates temporary fluctuations.
Why the other options are wrong
- A. This describes a PROB group, not BECMG.
- B. BECMG does not limit conditions only to the stated window; the change persists beyond it.
- D. This describes TEMPO conditions, which are temporary, not BECMG.
BECMG TAF Group
BECMG indicates a gradual and permanent change in forecast conditions expected within the specified time period, after which the new condition prevails.
- Contrasts with TEMPO (temporary) and PROB (probability)
- Time range shows when transition occurs, e.g., 1416 = 1400Z-1600Z
- New conditions are expected to persist after the transition window
Memory trick: BECMG = 'Becoming' a new normal — the change sticks around.