FAA Flight Control/SELCALL

From HF Underground

5547 Khz, USB. Flight traffic control for transoceanic flights, Central Pacific routes 1&2. Pilots are required to test the HF transmitter during pre-departure flight checks, and this can occasionally be heard along with general in flight traffic. Frequency is also used for SELCALL transmissions. This and other HF aircraft frequencies may be going away due to most of the major air carriers switching to satellite radio technology.