GPS instead of turn and bank

Danny,

I have been told that the heading
information from a GPS is good enough to do the function of a turn and bank
and allow emergency operations without having a visual horizon reference.


Aviation Consumer has tried flying only with reference to the instruments page
on a Garmin 296 and 496. That page emulates the standard six-pack derived from
GPS data. They say it worked. They also said the 5 Hz vs 1 Hz update rate of
the 496 improves the concept a lot.

--
Thomas Borchert (EDDH)

Dave,

So may I ask what was wrong with his other two paragraphs?


Download the free (I think) simulator for the 196, 296, 396 or 496
handheld GPS navigators from Garmin and try the instruments page.
You'll see what Ron means. In fact, IIRC the 296 is simulated in MSFS,
so maybe it is shown there.

--
Thomas Borchert (EDDH)

On Feb 5, 5:38 am, Mxsmanic wrote:
A GPS unit doesn't know if you're coordinated. And if your track _is_
changing, it doesn't know why.

[Disclaimer: the following post is for the purpose of clarification
to the greater aviation community. I realize that arguing with this
delta alpha is a complete waste of time.]

Your statement does not make sense. Of course the GPS does not know
if you're coordinated. I doesn't need to. You can see the ball
yourself. If the ball is caged, and your ground track is changing,
you are by definition in a bank. End of story.

Mxsmanic wrote:

Newps writes:


And why do you even remotely care what your heading is?


Sometimes you have to maintain a heading; sometimes you have to follow
a track.




So now you're changing the subject? Good one.

Mxsmanic wrote:

Newps writes:


True, but utterly irrelevant.


It's highly relevant. GPS can't be used as a bank indicator, nor can
it be used as a turn indicator. All it can do is measure changes in
your track, which it does by checking your position over the ground at
regular intervals. It doesn't know the attitude of the aircraft, and
it doesn't know if you are actually turning.


All you care about is that you're actually turning. Or not turning.
The GPS does very well at that. Irrelevant the attitude of the
aircraft, the turn coordinator isn't telling you that anyway.



The wind is irrelevant. Speed and rate of turn are all that is needed.


A change in the wind will change your track as measured by the GPS.


Irrelevant.




The GPS does not know if this is a turn or just a wind change. And if
you turn, the GPS cannot distinguish that from a wind change, either.


Yawn.

Thomas Borchert wrote:

Danny,


I have been told that the heading
information from a GPS is good enough to do the function of a turn and bank
and allow emergency operations without having a visual horizon reference.



Aviation Consumer has tried flying only with reference to the instruments page
on a Garmin 296 and 496. That page emulates the standard six-pack derived from
GPS data. They say it worked. They also said the 5 Hz vs 1 Hz update rate of
the 496 improves the concept a lot.




I think that's the crucial part. If the update rate is too slow it's
almost worse than nothing.

"Brad" wrote in message
ps.com...

If the ball is caged, and your ground track is changing,
you are by definition in a bank. End of story.


No.


A wind shift will also alter the ground track. Listen to MX, the "idiot
savant" of this newsgroup.

Karl

Aviation Consumer has tried flying only with reference to the
instruments page
on a Garmin 296 and 496. That page emulates the standard six-pack
derived from
GPS data. They say it worked. They also said the 5 Hz vs 1 Hz update
rate of
the 496 improves the concept a lot.




I think that's the crucial part. If the update rate is too slow it's
almost worse than nothing.

Even the 5 Hz would drive me nuts!

A few years ago I wrote my own Flight Management software. It
contains obvious things like a moving map, nearest airports etc. , but
it also contained a GPS derived attitude indicator. As has been
suggested here earlier, the GPS gives me lon, lat and hopefully
altitude. My program then actually calculates the rate of ascent/
descent and left/right turn. This coupled with the ground speed gives
you enough information to deduce what the horizon would look like.
Now it makes of course some assumptions, like that the turn is
coordinated, this can be easily verified by the slip/skid ball, which
BTW has a fairly high MTBF. The principles here are somewhat similar
to a partial panel. What makes this approach actually useful is that
it combines the GPS information into a very simple Attitude Indicator
like display. Now if you use a device like NavMan the update rate is
once every 2 seconds which renders this approach absolutely useless,
normally the cheap devices SirF2 and 3 outputs in the 1Hz (Once a
second) range. I have flown under the hood with my device and a
safety pilot and I am able to keep it right-side-up. I am about to
try it with the 5Hz (Garmin GPS18-5) and I am pretty confident that
the usefulness will be quite good. I have presented this approach,
which works on Pocket PCs to my local EAA chapter. I am thinking of
making it available, despite this controversial feature.
Take a look at the Flyer below.

http://www.monroemobile.com/Flyer.jpg

Cheers,
SwedeFlyer

Brad writes:

Your statement does not make sense. Of course the GPS does not know
if you're coordinated. I doesn't need to. You can see the ball
yourself. If the ball is caged, and your ground track is changing,
you are by definition in a bank. End of story.

I was talking about using GPS to measure turn and bank.

--
Transpose mxsmanic and gmail to reach me by e-mail.