GA

• general aviation

  ICAO

• glide angle

  General

• Go ahead, resume sending (to be used in AFS as a procedure signal)

  ICAO

GA has 3 meanings; the right one depends on context. A weather report, a NOTAM or an ATC clearance. Got a NOTAM full of contractions? Paste it into the decoder.

Source: FAA Order JO 7340.2 Contractions. Not for operational use.