This article doesn’t provide much original thought. It’s based on information I’ve been taught and information I’ve been read, so nothing in here is new, it’s just not covered so well in most instrument flying textbooks.

Mostly what we’re talking about here are flying the needles of the ILS because this is where people have the most trouble because this is where the needle is the most sensitive. However, this technique works on any “needle” you have to fly including VORs, GPS etc.

The basis of this technique is having the needle alive, by which we mean that the needle is not hard up against the stops on either side of the display, and the needle is not moving. We’re not worried about having the needle in the middle of the dial, that’s a refinement that can come later.

When the needle is not moving the heading the plane is flying is the “reference” heading, or the heading that assuming all things remain constant, accounts for the wind correction needed to track the desired course. If we’re flying towards the navigation aid then in fact if we keep the needle still our accuracy is improving and our course offset is decreasing. Since localizers and VORs provide measurements in degrees, the closer you get to the navaid tracking the same radial the closer you’ll be in actual miles to your desired radial. So that’s one thing we’ve got going for us, without doing anything we’re getting more accurate as we get closer.

It’s much easier to keep the needle still than it is to move it around the face of the CDI. Once the needle starts moving, especially if it starts moving with any speed or even accelerating stopping the needles movement can b very difficult. This is why instrument students tend to ‘S’ turn down the localizer. They’re focused on moving the needle to dead center and each time they get the needle to dead center by the time thy figure out how to stop the needle moving it’s half-way over to the other side of the dial and everything has to start again.

To keep the needle still make small corrections, preferably with the rudder as often using bank results in too high a rate of turn, in the direction of needle movement. Once the needle stops moving level the wings and watch. If you’ve lived a good and valuable life the needle will be dead still, otherwise it may still be moving, but it won’t be moving a lot, and since we don’t care where it ends up we can just make a very small change of heading, we’re talking half degrees here, in the direction the needle is moving and it’s sure to stop.

This bears some explaining – we turn towards the direction of needle movement, so if the needle is moving from left to right we turn to the right. It doesn’t matter which side of center the needle is on since we’re not trying to center the needle, we’re just trying to stop it moving. So even if the needle is on the left side of the CDI, if it’s moving left to right we turn to the right, “away” from the needle. That’s because our goal is to find the reference heading and stop the needle movement, we’re not trying to intercept the needle in the traditional “fly towards the needle” solution.

If you’ve got a heading bug and a spare hand, move the bug to the current heading. That’s your reference heading. You can safely ignore any other heading information you may have determined, this heading will hold the needle still. Unless the wind direction changes, and it might. If he wind does change then the needle will just start to move, apply a small correction in the direction of needle movement and stop it moving. We don’t care where it stops, it just needs to stop. Once it stops we’re OK – you can move the heading bug if you’ve got the time, but inside the FAF where this is most likely to be an issue the less extraneous stuff you get up to the better off you’ll be.

This wok for the glideslope as well – the glideslope is just a localizer on it’s side, we need to stop the glideslope needle moving by adjusting our rate of descent to hold the needle still. Again, where the needle ends up is not important, it’s whether it’s moving or not that’s the key.

We haven’t discussed actual headings here, because truth be known we’re not that interested in what the reference heading is, only that we know if we keep the plane heading in one specific direction it will cancel out any wind drift and hold a course. If we have some idea of the wind correction needed or the descent rate required for the glideslope then that can give us a fine starting point to use to find our reference heading and descent rate, but once nailed the needles still any previous information is no longer needed.