NDB approaches -- what are they good for?

(Michael) writes:

How about when you're doing the procedure turn? How do you know when
to start your turn to your final approach course? More mental math?

There are big marks on the ADF indicator every 45 degrees, just as
there are on the HI. Depending on which side I'm coming in from the
PT, I wait until the needle is close to the 45-degree mark to the left
or right of the top of the indicator, then turn in.

The inbound turn is actually one of the few places where the NDB
approach is easier -- the LOC sometimes comes across so fast that my
inbound turn from the PT becomes an S-turn, especially if I have a
tailwind (i.e. a crosswind for the final approach). The ADF always
gives me lots of warning as I approach the track and never forces me
to snap into a 30-degree bank just to stay within the protected area.

I hope that there aren't any instructors who force students to do
complex mental math for this kind of thing instead of just using the
big, easy marks on the ADF indicator. If instructors do that, no
wonder people hate NDB approaches so much!

More stuff to remember. The VOR needle keeps working the same way
throughout the approach.

Quite right. As someone else mentioned, though, the LOC(BC) approach
can be even more of a challenge. Not only do you have the reverse
sensing, which can be a big problem if you don't have special
equipment and you're not current with LOC(BC) approaches, but you also
have the exaggerated sensitivity near the threshold approach, at
exactly the time that you don't want to destabilize your approach by
chasing a wandering CDI.

I find it hard to believe that anyone could pass an IFR checkride by
chasing a CDI in a zigzag -- can they?

Yes. They can. I've seen it happen.

OK, now I see what you mean about the NDB approaches forcing
instructors to teach basic skills that they might otherwise neglect.
I don't particularly like that argument -- it's the same as the flawed
argument that teaching Latin helps people learn English grammar -- but
at least I can see where you're coming from. Perhaps raising the test
standards in that area would be a better solution.

For me, finishing up my instrument rating in Eastern Ontario, NDB
approaches and enroute navigation along LF/MF airways are simply a
fact of life and will likely be so for a while after my flight test.
I make no claim that NDB approaches are especially virtuous or make me
a better pilot, but the alternative (an IFR-certified GPS) is
prohibitively expensive -- a whole year's flying expenses for my
Warrior II -- and even then, it wouldn't let me fly IFR in much of the
far north.


All the best,


David

--
David Megginson, , http://www.megginson.com/