pilots only, please - gps or altimeter?

TxSrv writes:

Under VFR?

Yes, even under VFR. I said "if you depend on GPS for altitude
information," so it doesn't matter if you are VFR or IFR.

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

"john smith" wrote in message
I am trying to understand why Andrew and kontiki are the only two with
the correct answer.

Because Mr. Huck and Mr. birdog haven't had their moment yet. There are
reasons for fuel exhaustion beyond a pilot's control. They should feel lucky
that they can continue with their arrogant self-righteousness. Fly long
enough and s**t happens.

D.

Well, first I'd like to know where I am as Calgary is VERY close to
Mountains. So, my old 172 had a moving map with topography. But my newish
182 doesn't (yet). So, keep flying on course, declare an emergency to see if
you can raise terminal or whatever to identify you and your location, and if
not, check the coordinates off the GPS against the chart and go to plan B -
forced landing. I figure if I were in the mountains, I would already be dead
of flying into solid object, so a careful descent is in order.

Did this without reading the other replies. This may be interesting.

Marc

"houstondan" wrote in message
oups.com...
rather than hijack a perfectly good arcane science thread; i'll start a
new one 'cause the core question is a darn good one.

hypothetical situation: you're a blue sky vfr flyer and somehow you
wind up in the soup - after having gone 2 hours and 200 miles from your
take-off point , you wake up from a nice little nap and discover you're
inside the milk bottle.

gps(not waas) says nearest airport of any kind is 30 minutes away and
gas-totalizer says the fan stops in 10 minutes.

not mountainous but you ain't in kansas either todo...whatcha gunna
do??

really.

dan

"Mxsmanic" wrote in message
news
TxSrv writes:

Under VFR?

Yes, even under VFR. I said "if you depend on GPS for altitude
information," so it doesn't matter if you are VFR or IFR.


That doesn't make any sense in the real world. It might be more important in
a sim where you have no real depth perception to judge height. In the real
world under VFR conditions, it is much more looking out the window to avoid
running into the ground and other planes.

In cruise, it is easy to stay "well above the earth" and it is legally see
and avoid anyway. Specific altitudes are only recommendations to minimize
the chances of running into someone else but it's much looser than lines on
a highway. Even approaching an airport, anyone with a license could judge
pattern altitude and approach to a runway without an instrument.

In a sim, it is probably more difficult. Keep trying, you'll get there.

-------------------------------
Travis
Lake N3094P
PWK

Travis Marlatte writes:

That doesn't make any sense in the real world.

Maybe, but I'm not the one who described the scenario.

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

Howdy!

In article .com,
houstondan wrote:
rather than hijack a perfectly good arcane science thread; i'll start a
new one 'cause the core question is a darn good one.

....right. And you're looking for a fight with that subject -- and you
left the door wide open by not qualifying "pilot" at all.

hypothetical situation: you're a blue sky vfr flyer and somehow you
wind up in the soup - after having gone 2 hours and 200 miles from your
take-off point , you wake up from a nice little nap and discover you're
inside the milk bottle.

gps(not waas) says nearest airport of any kind is 30 minutes away and
gas-totalizer says the fan stops in 10 minutes.

not mountainous but you ain't in kansas either todo...whatcha gunna
do??

OK. What is the "core question" you refer to? Your subject and
your exposition do not quite agree.

yours,
Michael


--
Michael and MJ Houghton | Herveus d'Ormonde and Megan O'Donnelly
| White Wolf and the Phoenix narrowwares
Bowie, MD, USA | http://whitewolfandphoenix.com
Proud member of the SCA Internet Whitewash Squad

On Sun, 12 Nov 2006 19:52:44 +0000, Jim Logajan wrote:
Cut power and deploy the ballistic parachute.

Nawh...

"Eject! Eject! Eject!"

I'd be curious to have someone explain to me how GPS altitude
information is so inaccurate that I risk my life by setting my
altimeter with it. I have never been totally dependent on a GPS for an
altimeter setting, but I sure as heck would have no qualms about using
it if it came down to it. I am a terrible judge of how high I am off
the ground, and I'd rather put my trust into those five or six
satellites than my two eyes.

The simple math alone rules out the necessary accuracy, making the
rest of the system moot. If you depend on GPS for altitude
information, you may kill yourself while flying. It's as simple as
that.

On 12 Nov 2006 10:13:41 -0800, "houstondan"
wrote:

rather than hijack a perfectly good arcane science thread; i'll start a
new one 'cause the core question is a darn good one.

hypothetical situation: you're a blue sky vfr flyer and somehow you
wind up in the soup - after having gone 2 hours and 200 miles from your
take-off point , you wake up from a nice little nap and discover you're
inside the milk bottle.

gps(not waas) says nearest airport of any kind is 30 minutes away and
gas-totalizer says the fan stops in 10 minutes.

not mountainous but you ain't in kansas either todo...whatcha gunna
do??

really.

dan

interesting question.
aviate navigate procrastinate communicate

a more interesting one is "how do you unscramble an egg?"
it was one asked by Richard Collins in his book on flying ifr.
answer is that you cant.
your aircraft has got you through your little beddie byes by keeping
its wings level which is exactly what you need to do to continue
flying. trim the darn thing to fly level or climb slightly.
all ifr problems (all things being equal) start when the wings deviate
from level and you get into an acceleration.
keeping the aircraft unscrambled starts with keeping the wings level.

where is the gps telling you that you are located?
keep the aircraft on a level course and ferret out the wac charts.
whats the terrain altitude?
make sure you are flying higher than it :-)

where is the flattest terrain?
are there any areas of population nearby?
you would want to fly towards either if you only have 10 minutes fuel
left. definitely keep away from terrain higher than you.

you've made it this far in your sleep so it cant be hard going :-)
why panic now?
look around you for the darkest sky.
look around you for the lightest sky.
if you can see lighter sky (cloud) the chances are that it is broken
and sunlight is streaming down through a gap. head for it and you may
be able to find a hole and do a steep descending turn down under the
cloud.

if you have had a look and you are still clueless about what to do
then keep flying straight and level. trim the revs for maximum
endurance/minimum fuel flow and hope that you pop out of the cloud
eventually.
all decisions made in the first minute of a stressful situation are
wrong so take your time in making a decision.
dont give up but do try to formulate a plan withing the next 10
minutes :-)

Stealth Pilot (who is really a pilot)

On 17 Nov 2006 05:08:33 -0800, "Timmay" wrote:

I'd be curious to have someone explain to me how GPS altitude
information is so inaccurate that I risk my life by setting my
altimeter with it. I have never been totally dependent on a GPS for an
altimeter setting, but I sure as heck would have no qualms about using
it if it came down to it. I am a terrible judge of how high I am off
the ground, and I'd rather put my trust into those five or six
satellites than my two eyes.


very easy.
get a big piece of paper.
draw a long narrow triangle, one with a short base length and two
sides extending way way off to a point.

play around with trigonometry and see how much the length of the short
side varies when you calculate its length using the two long sides and
the included angle. notice how much the length of the short side
varies with tiny variations in the angle.

you have a similar sort of problem with the time intervals making a
triangle with the times being the long sides and the altitude being
the short side.

I've seen GPS altitudes while flying which were exactly the same
height as my altimeter was indicating. I've also regularly seen the
altitude up to 2,000ft out and one one flight it was calculating my
height as 5,500ft when I was actually doing a 500ft run along a
deserted beach.

fools use gps heights but they are no stupider than the software
engineers who made them available in the gps units in the first place.

Stealth Pilot
(garmin gps 2 plus user who never uses the gps height)