In article . com,
"Andrew Sarangan" wrote:
Jose wrote:
The CDI display
on Nav1 is pretty useless because it is not a real CDI.
I don't know what that means. When I use the CDI display (page 1 on the
nav screen) I find it quite effective.
Jose
That means you are not using the CDI to its full potential. A CDI gives
a _course_ to turn to, not a left/right indication. For that to work,
you need a full circle of numbers around the CDI.
If you have never encoutered this concept before, you should read this:
http://www.sarangan.org/aviation/art...or-article.pdf
Andrew,
I just read your article. The big problem with it is that it equates
"heading" and "track". For example, you talk about an OBS set to 210, with
a centered needle and a "FROM" (downward-pointing arrow) indication and say:
"030 lies in the direction of the station. This is the heading we need to
fly to track the course towards the station."
I'll agree that turning to a heading of 030 is a reasonable first estimate
until you figure out the right WCA, but as written, the article is just
plain wrong.
I also take exception to the general tone of the article, which is that the
CDI is a wonderfully designed instrument and whole generations of pilots
and instructors are idiots for not using it the way it was intended to be
used. It certainly is a cleverly designed instrument -- it's the best that
the brightest minds of the aviation world could come up with using the
technology of 50 years ago. You say things like:
"Given the simplicity of this technique, it is somewhat mysterious why this
is seldom taught during flight training".
There's really only two possible answers. One is that we're all idiots,
the other is that it's not really as simple as you make out. You think
it's simple, but, you're a college professor with a PhD. How many of your
students have this level of education?
You say:
"There might be a lesson in this. Some things are better left the way they
are. The VOR system might be a 50-year old technology, but it is one of
the greatest inventions in aeronautical navigation. It is really too bad
that we wonąt have them for much longer"
I can't disagree more. People vote with their feet. The VOR/CDI combo WAS
indeed a great invention. It was better than the ADF because it presented
better information to the pilot. The VOR/HSI was an improvement on that,
for the same reason, but never really penetrated the GA market because of
the high cost. The moving map GPS is an even bigger step up in
presentation (although the UI's for programming them still pretty much
suck).
People's brains have evolved over thousands (millions?) of years to process
visual information. If we're going to have good interfaces to people's
brains, we need to present them with information in the way those brains
are used to processing it. 50,000 years ago, some ancestor of mine could
look at the tree he was walking towards and understand that if he wanted to
get to the tree, he needed to turn left. Given a choice between inventing
technology to match my 50,000 years of visual experience, or training my
brain to understand what a 50 year old electro-mechanical gizmo is telling
me, I'll go with the GPS moving map.