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Questions on high altitude pressures



 
 
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  #21  
Old November 25th 08, 10:57 PM posted to rec.aviation.piloting
Mxsmanic
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Posts: 9,169
Default Questions on high altitude pressures

writes:

The point is that even with SA, GPS accuracy is pretty good and has nowhere
near 2 orders of magnitude altitude error compared to lateral as you stated.


You call a 500-foot error in altitude good?

Absolutely wrong.


All I have to do is look at my GPS and watch it wander up and down by tens of
metres at a time. GPS is not designed for vertical accuracy.

See the the data:

http://users.erols.com/dlwilson/gpswaas.htm

"The" data? It's just one person making experiments. I can do that, too; and
I get huge errors in altitude, so much so that I've never used GPS for
altitude measurements.

If you knew anything about real flying, you would know that you NEVER
use GPS as your altimeter under ANY circumstances for reasons entirely
unlrelated to GPS accuracy.


What are those reasons related to, if not accuracy?

If it's as accurate as you seem to believe, it should be fine for IFR. Go
ahead and use it for that, and make me a liar. Are you prepared to bet your
life on it?

But how would you know as you have never been in a real airplane with
a real altimeter and a real GPS?


I've been using GPS for many years. It's almost useless for measuring
altitude.
  #22  
Old November 26th 08, 12:05 AM posted to rec.aviation.piloting
[email protected]
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Posts: 2,892
Default Questions on high altitude pressures

Mxsmanic wrote:
writes:

The point is that even with SA, GPS accuracy is pretty good and has nowhere
near 2 orders of magnitude altitude error compared to lateral as you stated.


You call a 500-foot error in altitude good?


That's 492 feet with SA on, which as you've already acknowledged has been
off for a long time.

Absolutely wrong.


All I have to do is look at my GPS and watch it wander up and down by tens of
metres at a time. GPS is not designed for vertical accuracy.


YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.

See the the data:

http://users.erols.com/dlwilson/gpswaas.htm

"The" data? It's just one person making experiments.


I can point you to dozens of sites with similar data and the GPS
specs as well, but you could just do it yourself and admit for once
that you are wrong.

If you knew anything about real flying, you would know that you NEVER
use GPS as your altimeter under ANY circumstances for reasons entirely
unlrelated to GPS accuracy.


What are those reasons related to, if not accuracy?


Regulations, the nature of real air, the way real airplanes fly and
common sense.

Beg for some money, give the money to a CFI, and it will be explained
in detail to you.

If it's as accurate as you seem to believe, it should be fine for IFR.


Regulations, the nature of real air, the way real airplanes fly and
common sense.

But how would you know as you have never been in a real airplane with
a real altimeter and a real GPS?


I've been using GPS for many years. It's almost useless for measuring
altitude.


YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.

MY non-WAAS, aviation GPS receiver measures altitude that is within about
+/- 15 feet, or about +/- 4m, which is what everyone with a real GPS
gets.

So, to summarize:

You know nothing about GPS specifications.

You know nothing about aviation use of GPS.

Because you are such an arrogant, opinionated ass, you can't get a job
that would enable you to afford a decent GPS receiver.

That about sum it up?

I doubt the time accuracy on your piece of crap GPS is anywhere near
the nanosecond capabilities of a decent receiver either.


--
Jim Pennino

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  #23  
Old November 26th 08, 12:10 AM posted to rec.aviation.piloting
Viperdoc[_6_]
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Posts: 95
Default Questions on high altitude pressures

Anthony, what kind of GPS are you using- is it a Garmin 530/430 with WAAS?
How many satellites do you track at a time- or are you referring to playing
MSFS again and confusing it with reality?



  #24  
Old November 26th 08, 12:35 AM posted to rec.aviation.piloting
[email protected]
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Posts: 2,892
Default Questions on high altitude pressures

Viperdoc wrote:
Anthony, what kind of GPS are you using- is it a Garmin 530/430 with WAAS?
How many satellites do you track at a time- or are you referring to playing
MSFS again and confusing it with reality?


I would guess an old Tom-tom someone threw away.


--
Jim Pennino

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  #25  
Old November 26th 08, 06:25 AM posted to rec.aviation.piloting
Mxsmanic
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Posts: 9,169
Default Questions on high altitude pressures

writes:

YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.


The GPS system is not designed for vertical accuracy. It was designed as an
aid to lateral navigation. The geometry of the system does not favor vertical
accuracy.

I can point you to dozens of sites with similar data and the GPS
specs as well, but you could just do it yourself and admit for once
that you are wrong.


I can point you to dozens of sites that "prove" that Denver's airport overlies
a huge alien base underground, but that doesn't make it so.

Regulations, the nature of real air, the way real airplanes fly and
common sense.


If GPS were accurate, why would any of these other factors make a difference?

Beg for some money, give the money to a CFI, and it will be explained
in detail to you.


I know a lot more about how GPS works than the typical CFI.

Regulations, the nature of real air, the way real airplanes fly and
common sense.


See above. Why wouldn't regulations allow something that is as accurate as
you say?

YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.


They cannot be designed for vertical accuracy. The system itself is not
designed for that.

MY non-WAAS, aviation GPS receiver measures altitude that is within about
+/- 15 feet, or about +/- 4m, which is what everyone with a real GPS
gets.


How do you know?

I doubt the time accuracy on your piece of crap GPS is anywhere near
the nanosecond capabilities of a decent receiver either.


Actually, they all need nanosecond accuracy. But if you know how GPS works,
you already know that, right?
  #26  
Old November 26th 08, 06:26 AM posted to rec.aviation.piloting
Mxsmanic
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Posts: 9,169
Default Questions on high altitude pressures

Viperdoc writes:

Anthony, what kind of GPS are you using- is it a Garmin 530/430 with WAAS?


In real life? I have a handheld Garmin. In simulation? A 530 and a 430,
without WAAS (but they are always completely accurate in simulation, anyway).

How many satellites do you track at a time- or are you referring to playing
MSFS again and confusing it with reality?


In real life, up to twelve satellites simultaneously.
  #27  
Old November 26th 08, 06:27 AM posted to rec.aviation.piloting
Mxsmanic
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Posts: 9,169
Default Questions on high altitude pressures

Clark writes:

Of course mxy is ignorant of the current GPS performance and too stupid to
understand that the technology has improved.


The design has not changed, and unless the planet becomes transparent to GPS
signals, accuracy cannot improve much.
  #28  
Old November 26th 08, 07:35 AM posted to rec.aviation.piloting
[email protected]
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Posts: 2,892
Default Questions on high altitude pressures

Mxsmanic wrote:
writes:

YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.


The GPS system is not designed for vertical accuracy. It was designed as an
aid to lateral navigation. The geometry of the system does not favor vertical
accuracy.


You are making yourself look the fool more than ever.

Both the specifications and typical results for vertical versus lateral
error for SA on, SA off, and WAAS are all less than 2:1, not the 100:1
you claim.

I can point you to dozens of sites with similar data and the GPS
specs as well, but you could just do it yourself and admit for once
that you are wrong.


I can point you to dozens of sites that "prove" that Denver's airport overlies
a huge alien base underground, but that doesn't make it so.


Sure, you can find kook sites, but that is an irrelevant red herring.

GPS error has been studied and results published on the web by lots
of univerities, major corporations, and government agencies, including
the NIST and the FAA.

The full specifications for GPS are publically available.

All say you are wrong, wrong, wrong.

Regulations, the nature of real air, the way real airplanes fly and
common sense.


If GPS were accurate, why would any of these other factors make a difference?


Start with the fact that not all real airplanes have GPS and not all real
airplanes that have GPS have WAAS capable GPS and no real airplane has a
"pause" key and see if you can figure it out.

I know a lot more about how GPS works than the typical CFI.


From your statements so far, i.e. vertical error is two orders of magnitude
greater than lateral error, it appears you know nothing about GPS other
than how to spell it.

They cannot be designed for vertical accuracy. The system itself is not
designed for that.


Wrong, wrong wrong.

You might try reading the actual GPS system specifications before you
make such inane statements.

MY non-WAAS, aviation GPS receiver measures altitude that is within about
+/- 15 feet, or about +/- 4m, which is what everyone with a real GPS
gets.


How do you know?


By looking at the displayed GPS altitude while on the ground and comparing
that to the published field elevation.

By looking at the displayed GPS altitude and comparing to the surveyed
altitude of my location, e.g. my house.

That should be obvious to anyone with more than two functioning brain
cells.

I doubt the time accuracy on your piece of crap GPS is anywhere near
the nanosecond capabilities of a decent receiver either.


Actually, they all need nanosecond accuracy.


Wrong again.

Time accuracy is a measure of the error in the GPS time of day output,
just like for position, which includes a 1 pps signal.

Most consumer grade GPS receivers do not contain the circuitry needed
for nanosecond accurate time of day output.

And before you make yourself even more a fool on this point too, you might
want to go see what the National Institute of Standards and Technology
has to say on the subject.


--
Jim Pennino

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  #29  
Old November 26th 08, 07:45 AM posted to rec.aviation.piloting
[email protected]
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Posts: 2,892
Default Questions on high altitude pressures

Mxsmanic wrote:
Clark writes:

Of course mxy is ignorant of the current GPS performance and too stupid to
understand that the technology has improved.


The design has not changed, and unless the planet becomes transparent to GPS
signals, accuracy cannot improve much.


Wrong yet again.

SA turned off, differential GPS, WAAS, and LAAS.

--
Jim Pennino

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  #30  
Old November 26th 08, 07:59 AM posted to rec.aviation.piloting
John E. Carty
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Posts: 24
Default Questions on high altitude pressures


"Mxsmanic" wrote in message
...
writes:

YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.


The GPS system is not designed for vertical accuracy. It was designed as
an
aid to lateral navigation. The geometry of the system does not favor
vertical
accuracy.

I can point you to dozens of sites with similar data and the GPS
specs as well, but you could just do it yourself and admit for once
that you are wrong.


I can point you to dozens of sites that "prove" that Denver's airport
overlies
a huge alien base underground, but that doesn't make it so.

Regulations, the nature of real air, the way real airplanes fly and
common sense.


If GPS were accurate, why would any of these other factors make a
difference?

Beg for some money, give the money to a CFI, and it will be explained
in detail to you.


I know a lot more about how GPS works than the typical CFI.

Regulations, the nature of real air, the way real airplanes fly and
common sense.


See above. Why wouldn't regulations allow something that is as accurate
as
you say?

YOUR GPS receiver is not designed for vertical accuracy because you are
too poor to be able to afford a decent one.


They cannot be designed for vertical accuracy. The system itself is not
designed for that.

MY non-WAAS, aviation GPS receiver measures altitude that is within about
+/- 15 feet, or about +/- 4m, which is what everyone with a real GPS
gets.


How do you know?

I doubt the time accuracy on your piece of crap GPS is anywhere near
the nanosecond capabilities of a decent receiver either.


Actually, they all need nanosecond accuracy. But if you know how GPS
works,
you already know that, right?


I usually refrain from this kind of post. However, you absolutely must be
one of the following:

A: A computer simulator "pilot"
B: An Idiot
C: Both A and B

:-)


 




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