Hint # 2 was a mental exercise that can and should be mastered on the ground for the computation of headings, which should be second nature. .

Hint # 3a now get's to the essence of aircraft control. This is about the secrets of flying a one dot ILS Approach.

Any of you who have gone through flight training will remember your instructor badgering you about "overcorrecting". i.e. your turns are too fast, your banks are too steep, your intercept angles are too large, etc. .

This hint is what that is all about.

For an instrument rating, all you have to do is to keep the needle somewhere on the indicator. This will get you somewhere near the airport, but it is really poor precision.

When you go for your Airline Transport Pilot Rating (ATP) you have to make your approach within the bullseye. Anything less is disqualifying. This is a one dot approach on the ILS indicator.

This means that HORIZONTALLY your maximum deviation is one dot on the indicator AND VERTICALLY your maximum deviation is one dot on the indicator. You must be able to keep it within one dot if you want to pass your ATP flight check. (Even when the examiner cuts one engine, you are expected to keep it in the box).

This requires some close attention to the needle because if it even starts to twitch, you are almost out of the box.

To give you some idea of how close the tolerance is, when you are at the middle marker, the box you have to stay in is 75 feet wide and 35 feet high. i.e. in a large airplane the wingtips are probably outside of the box you are flying in.

But, not to worry. As in most things, there are "tricks to the trade" and here they are.

You are going to have to establish a correct heading to hold you on the localizer, as soon as possible and you are going to have to nail the correct rate of descent immediately.

When you establish yourself on the localizer, the first thing you want to do, is to ESTABLISH YOUR POWER SETTING. This is usually a manifold pressure setting that will allow the airplane to descend EXACTLY ON THE VERTICAL GLIDEPATH. In a light airplane it is about 13 inches of Manifold Pressure.

However, there is a trick here that you need to watch out for because it will mess up the best approach if you are not aware of it.

As you descend, your engine starts to develop more power as it gets closer to the ground because of the increasing atmospheric pressure. During the normal 2000 foot descent, you will pick up about 2 inches of manifold pressure by the time you hit the middle marker. This will cause a perfectly trimmed airplane to ride up on the glideslope and get out of the box if you leave it alone.

So, about every 1000 feet down you are going to have to reduce power about 1 inch of manifold pressure to compensate for this tendency. This will keep the airplane sliding down the rails toward the runway, within the box.

I try and know my airplane so well that I know what sort of power setting it takes to hold the glide slope at the glide slope intercept point. Then it is merely a matter of putting that number on the manifold pressure setting and the descent is under control (for the moment..It wont last long).

At that point, I calculate how much altitude I will lose between the point I start descending and the middle marker or the missed approach point. (Ideally, you want to be exactly on the centerline at the missed approach point).

If I start at 2900 feet and I know that the missed approach altitude is at 800 (200 ft AGL) then I expect to have to take off 1 inch of manifold pressure at 1900 feet and make another adjustment of about 1/2 inch at about 1300 (500 feet above the Decision Height).

This will allow the airplane a very slight tendency to ride up on the glideslope when I am near the decision height which is what I want.

I want to keep the airplane needing very slight forward pressure to maintain it exactly on the glideslope. I like to stay about a half dot above the glideslope ( like my wheels are down there on the glideslope is the way I think about it). Then if I relax the pressure, the airplane at least will not dive into the ground.

Then any correction I have to make is either made with the trim or with very slight forward or back pressure when I see the needle twitch.

This frees me up to concentrate on holding the horizontal alignment with the established wind drift correction angle.

When the power is managed in this manner, the airplane will, for the most part, behave nicely, requiring very little control input to stay within the box.

The next part of this problem is to very early on, establish a proper wind correction angle so that you can concentrate on maintaining one heading and flying that heading plus or minus 1 degree (Hint 3).

You do this by taking a cut at the wind, seeing if the needle moves, making a correction into the wind to get to a point quickly where the needle stabilizes on the center line and then concentrate on maintaining your heading and keeping the plane on the glideslope.

With a little practice, being aware that the engine is putting out more power near the ground so you take off that last 1/2 inch, you will find that the airplane will make a very stable approach and you will be able to easily hold things within one dot throughout the approach.

Last, you will know, that if you are ever in a situation \ where the weather goes below minimums and you have to land or run out of gas, you will hit the runway, rather than the taxi strip or a hangar in a zero zero condition.

This is one of the benefits of flying to ATP standards rather than to Instrument Rating Standards. It keeps you sharp, and in reality, is a whole lot less stressful.

After you have done it the first time, you will find that it is much easier to do it the second time.

Good Luck

When you get into using this technique for instrument approaches, it makes life easier also, again because things don't happen so fast, at a time when you really have your hands full. .

If you have questions you may E-Mail me at

atpcfii@ferrypilot.cjb.net Fred H. QuarlesATP-CFII
888-595-9131

- End of Hint # 3a -

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5. Have a Nice Flight