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MEADE1990 created the topic: HF Frequencies
On the PCA there are three frequencies listed for each of the 3 RDARA zones.
If you punch in their location code into location breifing to get the most up to date frequency you are given the following (see attachment)
If you're asked in the exam, which frequecy to use at a specific location, which do you use? I've been trying to hunt this answer down for hours.
While HF transmissions have the advantage of long range communication beyond 'line of sight' they are also affected by sun spot and ionospheric disturbances. This can result in particular HF frequencies being more or less effective as ionospheric conditions fluctuate. Because of the random nature of these disturbances, pilots are advised which frequencies are working best at a given time and in a given area. The 'primary HF frequency' can be obtained from briefing or passed to the pilot while he/she is still in VHF range. I don't think you will find a specific reference to this in the commonly available documents. Maybe someone can suggest one.