Violating Airspace with GPS

In article , Ron Natalie wrote:

Your information on RAIM is wrong. What is unique about the RAIM used in IFR
approved GPS's is not that it determines when the satellite geometry is giving you
an error NOW, but computes if it will fail while during the expected duration of flying
an instrument approach.

That's RAIM *prediction*. RAIM is very capable of failing during an approach if
you don't check the prediction ahead of time, at least on our Garmin 430.

I don't know what John's information on RAIM is, since it will be two or three
hours before his books is downloaded.

Regards,

Mike

I guess I still wasn't clear on what I was trying to say. A GPS is
great for knowing where you are on a pre-planned course. A GPS moving
map isn't good for much of anything.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.




Gene Seibel wrote:
...snip... A GPS is
great for telling you where you are, but you've got to know where you
want to be first. I seldom use my moving map.

Completely agree except for one point...

A GPS is excellent at *knowing* where you are, but very few of them (if
any) can transfer that information to you in a suitably efficient way.
So I disagree that they are "...great for *telling you* where you
are..." :-) Trying to interpret that tiny moving map is where the
distractions occur and the potential for error...

Concentrating on CTS, Bearing to next waypoint, and XTE for a
well-planned (and correctly entered) route, is so much easier and more
informative.

Perhaps the GPS is making us forget that it is so much more important to
know where to go next, than it is to confirm where you are now.

Gene Seibel wrote:

I guess I still wasn't clear on what I was trying to say. A GPS is
great for knowing where you are on a pre-planned course. A GPS moving
map isn't good for much of anything.

Huh? Wouldn't be without mine. A GPS without a moving map is useless.

"Gene Seibel" I guess I still wasn't clear on what I was trying to say. A
GPS is
great for knowing where you are on a pre-planned course. A GPS moving
map isn't good for much of anything.

"Icebound"
Concentrating on CTS, Bearing to next waypoint, and XTE for a
well-planned (and correctly entered) route, is so much easier and more
informative.

I am somewhat in disagreement on the usefulness of the map: I actually
consider the GPS map to be a very useful feature. I even consider this to
be the case in low resolution models such as the GPS III Pilot. However, I
feel that the map display is insufficient without the assistance of changing
the data fields displayed on the map page to something more useful. The map
is good at adding context to the data fields and the data fuilds are good
for adding precision to the map. I like TURN (TRACK-BEARING), OFF COURSE
(XTE), DISTANCE, and WPT (I like a textual indication of the waypoint--
accurately navigating to the wrong place is pointless).

I very strongly agree that a properly preplanned course with reference to
the proper charts is mandatory.


John Bell
www.cockpitgps.com

(Gene Seibel) wrote

A GPS moving map isn't good for much of anything.

BULL****!!! Strong statement to follow.....

Bob Moore
ATP CFII

Gene,

I guess I still wasn't clear on what I was trying to say. A GPS is
great for knowing where you are on a pre-planned course. A GPS moving
map isn't good for much of anything.


Well, I couldn't agree less. GPS moving maps are a WONDERFUL tool for
situational awareness. In fact, beyond the AI, it doesn't get much
better. If you think wasting your time interpreting arcane needles is
better, it may be time to tune down the machismo ;-)

--
Thomas Borchert (EDDH)

On Mon, 03 Nov 2003 17:01:01 +0100, Thomas Borchert
wrote:

Well, I couldn't agree less. GPS moving maps are a WONDERFUL tool for
situational awareness.


Did you mean to say positional awareness? Positional awareness is
only a small part of situational awareness.

Did you mean to say positional awareness? Positional awareness is
only a small part of situational awareness.


Well, if what you say is correct, I guess I was correct to say
"situational awareness". IMHO it gives you more than positional
awareness.

--
Thomas Borchert (EDDH)

"John Bell" wrote in message . com...


Actually, my response to Ron Natalie was a little more than tongue in cheek.
It was somewhat of a combination of defensiveness and worry that I might be
spreading bad information. Ron's statement that my explanation of how GPS
works: "while one of the common ones often espoused
has no basis in reality. This is not how GPS works" has me curious.

The "overlapping spheres" model is NOT how GPS works. It's the same as the
stupid flashing light analogy for VOR. It perhaps gives someone some concept,
but it's not accurate at all. The way GPS works is to use pairs of satellites
to determine hyperbolids which are intersected with ones generated from other
pairs.

Didn't realize that it took a lot of machismo to determine if a needle
was pointing left or right. But I've been wrong before.
--
Gene Seibel
Hangar 131 - http://pad39a.com/gene/plane.html
Because I fly, I envy no one.



Gene,

I guess I still wasn't clear on what I was trying to say. A GPS is
great for knowing where you are on a pre-planned course. A GPS moving
map isn't good for much of anything.


Well, I couldn't agree less. GPS moving maps are a WONDERFUL tool for
situational awareness. In fact, beyond the AI, it doesn't get much
better. If you think wasting your time interpreting arcane needles is
better, it may be time to tune down the machismo ;-)