The ADF instrument in Air Navigation uses GPS track information and does not receive any radio waves. It can still be of value for practicing ADF navigation.
The top part is the ADF indicator. The yellow needle is pointing towards the selected waypoint that corresponds to the longitudinal axis of the aircraft. The compass card can be manually rotated using touch and swipe up/down gesture on the left or the right of the indicator. This way you can set the ADF to the magnetic heading. Below the main indicator the name of the active waypoint is displayed as well as the distance from the waypoint (great circle distance) and GPS accuracy. It is possible to select any kind of waypoint (Airports, VOR, NDB, etc) as an ADF target waypoint unlike with a real ADF which requires NDB or AM transmitters as waypoints. You can select a new waypoint from the database with the blue disclosure button on the bottom part of the instrument. Please read «Selecting waypoints from the database» to get information about waypoint search and selection.
A “NAV” warning flag will let you know that you should NOT trust the ADF indicator in the following cases:
- No waypoint is selected for the instrument;
- The waypoint distance is over 250 nautical miles;
- The GPS accuracy is less than 2.5 nautical miles.
Note: remember that you will ONLY find the spinball at the bottom of the instrument on iPhone/iPod Touch devices.
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