PPRuNe Forums - View Single Post - Question: An aeroplane is travelling away from an NDB on a track of
Old 17th Nov 2018, 09:42
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Another observation about outbound NDB tracking from my IR days. I've never understood why they taught NDB tracking using that stupid "push the head, pull the tail" business. An RBI is a really simple instrument and you only need one rule whether you're tracking to or from a beacon: "Steering track plus X, looking for track minus X" (or vice versa) where X is your drift angle. If the arrow's pointing to the right of your mark, it's a fly-right indication, if it's pointing to the left, fly left.

In the OP's example, the track is 145 degrees and the heading is 140 degrees, so the rule is "Steering track minus 5, looking for track plus 5".

If you're tracking to the beacon, in still air the arrow should be pointing at the 360 deg mark. "Steering track minus 5, looking for track plus 5". So to be on course the arrow should point at 005. If the arrow is right of 005, it's a fly-right indication and vice versa.

If you're tracking from the beacon, just keep looking at the arrow. In still air the arrow should be pointing at the 180 deg mark. "Steering track minus 5, looking for track plus 5". So to be on course the arrow should point at 185. Just as before, if the arrow is right of 185, it's a fly-right indication and vice versa. Maybe you get a fly left indication and decide to increase the drift correction to 15 degrees to get back on track. "Steering track minus 15, looking for track plus 15" - so when the arrow points at 195 degrees, you're on track.

Incidentally, this exact same rule also works for things like passing abeam the beacon in an NDB hold. You steer your outbound heading, with perhaps a total of -20 degrees of drift correction from the outbound track. In still air you'd be looking for the 90 (or 270) degree mark. "Steering track minus 20, looking for track plus 20". When the needle passes the 110 (or 290) degree mark, you're abeam.
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