The initial situation is:
Please refer to the following page for more information on the cockpit instruments we are using: Radio-Magnetic Indicator
In order to make the interception manoeuvre, you must tune the radio equipment:
After the instrument tuning, you can follow the progress of interception following the needle on the RMI instrument.
If you do not know the distance from the beacon, do not anticipate an interception turn or you can intercept the NDB track very far from your position.
For efficient radial interception, we advise to cross the track first.
With maintaining heading, you will normally cross the radial.
In the example, the needle points toward the beacon at 060° for the 240° track
At this time, as we want to follow the 240° NDB track inbound, we shall turn our aircraft to 060° heading.
For information, if you want to follow the 240° NDB track outbound, you shall turn your aircraft to 240° heading.
We are turning to heading 060°.
After the turn, we want to follow the 240° track inbound of the NDB:
If the aircraft turns clockwise (to the right), just add 15° to 30° to the course, or if the aircraft turns anticlockwise (to the left) just remove 15° to 30° from the wanted heading
Now you start to turn for intercepting the radial smoother, using a 15° to 30° interception angle.
If you estimate that the overshoot is not important, you can select a 15° interception angle, otherwise select 30°. The exact instant for the last turn is sometimes difficult to know. If you are close to the NDB, then you can initiate the turn sooner than if you are very far from the beacon.
The next figure shows:
A lower angle than 15° will impose a late interception or a non-possible interception when facing heavy crosswinds.
A higher angle will create another overshoot and another interception cycle.
In this picture, you can see that the 240° track of the wanted NDB is intercepted and you start to follow this track:
In the next figure, you will find: