These are Hourly Area Predictions (HAP) of HF communication frequencies based on current observed conditions in the European ionosphere.

HAP charts are designed for communications between a specified base and mobile within a nominated area.
• Each chart shows colours which represent the recommended HF frequencies for contacting the base or mobile within the area bounded by the chart for a particular hour.

• The geographic zone, which is variable, is represented by a map showing latitude and longitude.

• Charts are in Universal Time (UT).