NDB Chart Question

[RyanbATC]

Ok dokie - no need to discuss NDB's vs GPS (lol) but I have question regarding this NDB approach into Oconto, WI

http://naco.faa.gov/d-tpp/1003/06337NG29.PDF

What I have for equipment is an HSI and an ADF indicator with a moveable card under it.

I started by trying to line up the card with my heading (from the hsi) but just got screwed up that way. So I left it where it was and imagined the needle overlayed onto my HSI. From the chart we see the final approach course (or bearing whatever its called) is 301. From my picture here I presume I'm slightly right of course? I'm heading 300-ish and if I were to imagine the adf needle on my HSI it would point at about a 295. How do I know what my deviation is off the final and how do I correct it? Do I turn toward the needle or away??? That's what confuses me the most. Also, when I'm flying outbound prior to reaching the PT, again, do I correct towards the needle or away?

Thanks for any help...

[Brett_Henderson]

NDB approaches (while IMC) really test (and strengthen) your piloting skills. I'd not want to fly IMC as a passenger, with pilot who hadn't mastered them.

(I answered this question at one of the other forums)

[jeroen79]

When you are too far 'above' (on this chart!) the approach course the ADF will point to a bearing lower than 301.
When you are 'below' it will point to a higher bearing.

The ADF needle will move from the aircraft's nose towards the aircraft's tail as you pass the NDB.
When the desired course is between the nose and the NDB's bearing or even on the opposite side of the nose you will kep deviating.
If the desired course is between the tail and the NDB's bearing and on the same side you are moving towards that course.

It is simple geometry. Draw it out or visualize it here.

A quick picture:
If the desired course is within the red arc you are deviating. if it is within the green arc youre closing.

[NikeHerk67]

Ok dokie - no need to discuss NDB's vs GPS (lol) but I have question regarding this NDB approach into Oconto, WI

http://naco.faa.gov/d-tpp/1003/06337NG29.PDF

What I have for equipment is an HSI and an ADF indicator with a moveable card under it.

I started by trying to line up the card with my heading (from the hsi) but just got screwed up that way. So I left it where it was and imagined the needle overlayed onto my HSI. From the chart we see the final approach course (or bearing whatever its called) is 301. From my picture here I presume I'm slightly right of course? I'm heading 300-ish and if I were to imagine the adf needle on my HSI it would point at about a 295. How do I know what my deviation is off the final and how do I correct it? Do I turn toward the needle or away??? That's what confuses me the most. Also, when I'm flying outbound prior to reaching the PT, again, do I correct towards the needle or away?

Thanks for any help...

A "radio magnetic indicator RMI" would show a reference to the direction you were flying and would point in the direction you had to fly to get there. An ADF, however, is just a dumb “homer” that simply points to the NDB. The more sensitive the needle is to directional changes the closer you are to it. In this approach use your Nav 1 and/or Nav 2 radios (or both) and set for NMN, 212 degree radial, and GRB, 013 degree radial. The closer the VOR indicators come to lining up the closer you are to the NDB and R/W. The DME from MNM is 21.4nm and from GRB is 22.8nm.

NDB approaches are usually accompanied by another distance measuring device, either at the airport of offset like this one..

PS It's like flying to a fixed point. Importan to keep the needle straight and your heading at 301 degrees. Those two conditions must exist. Example: A cross wind could blow you off course, the needle could be straight up indicating you were flying toward the NDB, but if your course isn't 301 degrees your not on the R/W heading, although a slight turn tothe left once you see the R/W is required as well.

[lnuss]

In addition to the above good info, you might think of it more simply, under no wind. With no wind, you're on course if the ADF needle is pointing at 0º relative bearing (that is, straight ahead) and your heading is (in this case) 301º. This would be pointing at 120º on the ADF indicator as you have it set up in the picture above.

Incidentally, in the pic you provide above in your initial post, you have the "heading" indicator at 120º even though your actual heading is about the 300º mark. IF you're going to have the ADF instrument set that way it should be set to 301º (the desired course). Otherwise, it should be set to 0º, thus making it a relative bearing indicator, which for me would simplify it a bit.

So when you're on course, the needle will basically show your wind correction angle.

[olderndirt]

Is there no ADF function on that HSI?

[jeroen79]

Not on the KI525.

[Artkl]

Your heading is 300 degrees and the ADF needle is 5 degrees to the left. Your course from here to the NDB is 295 degrees. You are to the right of the 301 degree course. Turn left to a heading of, say, 290. When the ADF needle reaches 11 degrees to the right, you are crossing the correct course to the NDB, so start the turn back to the right earlier, depending how fast the needle is moving, so you can roll out on course. How much you lead the turn will depend on how the wind is affecting your ground speed. Your turn should be to a heading that corrects for drift.

I suggest you Google something like "adf approaches" to learn how to do these approaches. I also suggest that you leave the ADF card at zero, and go by degrees to the right or left of the nose.

Hope this will get you started in the right direction.

Art

P.S. When you say "movable card," does that mean you can rotate the card with the knob or does it mean it's an RMI? I assumed it was a fixed card that you can rotate.

[louross]

Personally if you were flying with me I'd tell you the same thing INUSS did- and that would be to set your card to 0 degrees. Then we could start talking technique.
lr.