more bitching about the IFR written - CDI left/right versus north/south/etc

There are a whole bunch of useless questions that you just have to get
through. Like the one where you have to pick which aircraft corresponds
to the given CDI indications. Who cares where the aircraft is. You will
no longer be there by the time you blink. What matters most is which
direction you have to turn to. Unfortunately, not only does the FAA
teach this contorted method of CDI interpretation, the majority of CFI's
also teach this way, and many are not even aware that there is a simpler
way. I wrote an article about this and sent it to a few magazines, and
it was turned down because they thought that this method was too
'controversial'. You can see my article at
http://www.geocities.com/asarangan/aviation.html



"G. Sylvester" wrote in news:Bi5Dd.8613
:

A month or two ago there was a thread about CDI indicating north/south
vs. left/right in particular on front course and back course LOC.
I'm studying for the IFR written and not in a single place
does the FAA use north/south. Again I'm banging my head
wondering does a lowly IFR student like me have to scream
learn the wrong way. Further they have questions about MLS
approaches?
Has anyone ever flown one or even seen one? I don't
even know what equipment is required for one. A historical
note about this, the founders of the company I work for
were (partial?) inventers of the MLS back in I think the 1940's
or early 50's. One of the brothers (Sig Varian, I think) was a
pilot for a major but ended up biting it while
landing in Mexico at night. He intended to land on
the beach but ended up putting it in the drink.

The same bitching goes to the lack of reference to technology.
I really can't imagine hand flying in the soup, thunderstorms
around, turbulence, at night, etc. and playing around with
an E6B. Umm, how long does a leg take, ummm, give me
2 seconds and the 430 will take care of that. Of course
double check the 430 but an E6B is a bit out dated. It works
and works without batteries but if things are that bad
all around, the last thing I'm doing. If hells breaks loose
and needed to use one, I think I'd declare an emergency over
121.5.

sorry to vent.....and no need to remind me how the FAA
is screwed up. Overall though I gotta give them a LOT
of credit as it seems like one of the few big government
agencies that has it reasonably together.

Gerald Sylvester

wrote in
:

On Thu, 06 Jan 2005 11:52:39 -0500, Ron Natalie
wrote:

The OBS has no meaning to a CDI when using a localizer.
It's left or right of the localizer beam where "left and right" is
defined as looking inward on the front course. It's only when the
pilot's left and right is reversed (as they are looking inward on the
back course) that things are "reversed."


This is not true. The OBS ring has no effect on the needle, but it
certainly has meaning.

If the OBS ring is set to the inbound (only) localizer course, it can
be interpreted exactly as the equivalent VOR course.


Exactly. Glad to see someone else using a more sensible interpretation.

No, it is not just a reminder, it is a tremendous aid in interpretation.
Reverse sensing is all in your head. The aircraft or the CDI does not
know reverse sensing. Read this article:
http://131.238.38.204/~sarangan/avia...or-article.pdf





Andrew Gideon wrote in
online.com:

wrote:

If the OBS is set to the course, you can immediately discern whether
you are north or south of an eastbound course, for example. You can
do this by looking at a properly set OBS ring, and at which way the
needle is leaning.

Setting the OBS during a localizer approach is a good mnemonic. I do
that. It's also a good habit.

But it doesn't really impact *interpretation* of the CDI's display
(unless one forgets the course marked by the localizer, in which case
the OBS setting saves having to look down at the plate).

Using your example, the OBS doesn't do anything but remind you that
the course indicated by the localizer is eastbound. Useful, true, but
I'd not consider that a part of the interpretation process. I make
this distinction because, unless I forget the course, I never need to
look at the OBS to discern the meaning of the CDI.

- Andrew

The CDI tells you which heading to turn to if you dial in the correct OBS.
Which do you think is more useful command: turn left, or turn to a heading
of xxx?




"C J Campbell" wrote in
:


wrote in message
...

The OBS has much meaning to a CDI when using a localizer course,
if you just know how to interpret said meaning.

It has no meaning to the CDI, which after all is an inanimate
object. If
you
are properly trained it should have some meaning for you.

When I use words, they mean exactly what I mean for them to mean,
nothing more and nothing less.

Very well, what does the OBS mean to the CDI on a localizer?

The CDI tells you which heading to turn to if you dial in the correct OBS.
Which do you think is more useful command: turn left, or turn to a heading
of xxx?

If I'm already pointing more or less in the right direction, "turn
left" is more useful. If not, the actual heading is.

When on an approach, I'm pointing more or less in the direction I want
to go, and I use the CDI to make small corrections to keep on the
flight path I want. So long as these corrections remain small, and I
remain more or less on the localizer, all I need is "a little more
left". The command "turn to heading xxx" requires me to figure out
how to get to xxx. "turn a little left" does not.

Jose
--
Money: What you need when you run out of brains.
for Email, make the obvious change in the address.

What you are saying is true. The problem is when you are not aligned
with the correct direction, either because you are being vectored, lost
or some other reason. When you are being vectored (or intercepting from
a PT), how do you tell whether you have blasted through the course, or
still heading towards it?? By the time you figure it out using the
left/right interpretation, you will have gone several miles out. It is
trivial with the heading interpretation. Another example is cross
radials. Some fixes on approaches are defined by a VOR cross radial. How
do you know whether you have passed that fix or still heading towards
it? Again, this is trivial with the heading interpretation, but
significantly more difficult with the left/right interpretation. I can
give you many more examples. However, I do agree with you that
left/right works when you are more or less aligned with the course. But
the important point is that it work ONLY in that situation. The other
technique works in ANY situation.





Jose wrote in
m:

The CDI tells you which heading to turn to if you dial in the correct
OBS. Which do you think is more useful command: turn left, or turn
to a heading of xxx?

If I'm already pointing more or less in the right direction, "turn
left" is more useful. If not, the actual heading is.

When on an approach, I'm pointing more or less in the direction I want
to go, and I use the CDI to make small corrections to keep on the
flight path I want. So long as these corrections remain small, and I
remain more or less on the localizer, all I need is "a little more
left". The command "turn to heading xxx" requires me to figure out
how to get to xxx. "turn a little left" does not.

Jose

On 6 Jan 2005 22:40:48 -0600, Andrew Sarangan
wrote:

Unfortunately, not only does the FAA
teach this contorted method of CDI interpretation, the majority of CFI's
also teach this way, and many are not even aware that there is a simpler
way. I wrote an article about this and sent it to a few magazines, and
it was turned down because they thought that this method was too
'controversial'.


It is this kind of stoneage thinking in aviation that is the reason,
for example, that we can log 20 hours of instrument time on totally
ancient, obsolete, and archaic potentiometer-driven simulators, but
only can get 10 hours on a modern, state-of-the-art computer-driven
simulator with many times the capabilities and function.

There is much about aviation stuck in a time warp. Personally, I'm
surprised that we have moved as fast as we have with GPS, (which is
about half as fast as we could and should have.)

wrote in message
...
On Thu, 6 Jan 2005 16:07:08 -0800, "C J Campbell"
wrote:


wrote in message
.. .

The OBS has much meaning to a CDI when using a localizer course, if
you just know how to interpret said meaning.

It has no meaning to the CDI, which after all is an inanimate object.
If
you
are properly trained it should have some meaning for you.

When I use words, they mean exactly what I mean for them to mean,
nothing more and nothing less.

Very well, what does the OBS mean to the CDI on a localizer?


The information on the OBS, combined with the information from the
CDI, augmented by information from the DG, tells you, at a single
glance:


Yes, it tells me something, but what does it mean to the CDI? You said your
wording was deliberate and specific.

"Andrew Sarangan" wrote in message
1...
The CDI tells you which heading to turn to if you dial in the correct OBS.
Which do you think is more useful command: turn left, or turn to a
heading
of xxx?

Yes, it tells me something, but what does the OBS tell the CDI on a
localizer?

"Andrew Sarangan" wrote in message
1...
There are a whole bunch of useless questions that you just have to get
through. Like the one where you have to pick which aircraft corresponds
to the given CDI indications. Who cares where the aircraft is. You will
no longer be there by the time you blink.

Are you saying that the aircraft moves from one quadrant to the other in the
blink of an eye?