Ideal watch?

How do you think your ears would feel if they only started preasurization
upon reaching 8000'?

Mike
MU-2


"TTA Cherokee Driver" wrote in message
...
Jim Fisher wrote:

wrote in message
Of course, it won't work in a

pressurized airplane.



I've always been curious about this: Wouldn't the altimeter still read
an
increase/decrease in altitude? No, the altitude would not be correct
but
for a backup to keeping the shiny side up in IMC it would have some
value,
right?


My wife gave me one of these watches for my birthday. Its altitude is
pretty much dead one if I set it right in a non-pressurized airplane.

I took it on a B737 business trip, figuring that since airlineres are
pressurized to 8000 feet it should work up to 8000 feet, and it's at
those lower altitudes that I really wanna know how high we are since
that's when theymake you turn off GPS receivers and such. I naively
thought that the cabin was not pressurized until 8000 and then the
pressurization was turned on at that point to keep it constant.

Imagine my disappointment when on takeoff roll our "altitude" dropped
over 100 feet and stayed there until we were several thousand feet up,
only gradually easing up to 8000. Learn something new every day about
how airlines work.

Has anybody tried a Suunto? King Schools sells them. They're not
cheap! They are huge however. I've never found anyone who sells them
locally. I'd like to try one on. They definitely have a unique look.
Dave

Brinks wrote:
I've been off looking for a good aviation watch. I've looked at Citizen
Skyhawk watches, which look cool, but they don't have a backlight, which I
thought would be bad (good?) for flying at night. And I've seen some
others that are all digital, but I like having the hands for a timer. And I
found one that vibrates, which I thought would be really handy for switching
tanks and things, but it didn't have hands. So, I was wondering, what would
everyone like to see as a minimum set of features in an ideal watch? Here's
my list -

1) Analog hands and second hand for timing things
2) Digital clock set to Zulu time so I don't have to bother my small brain
with those pesky conversions
3) Backlight so I can see it when I'm flying at night
4) Vibrating alarm so I remember to do routine things like switch tanks.
5) Nifty E6B ring around the outside that I really can't see, but really
impresses the chicks at the bar

What say you?

Chris

"John Galban" wrote in message
om...
"smf" wrote in message
news:WZ9Eb.13862$HQ.12885@okepread02...
snip
I have a Atomic clock at home to keep it
accurate. Although I can get a little "Anal" with the atomic clock.

You have an atomic clock at home?!? Very impressive. I always
wanted an atomic clock of my very own, but could never find an
affordable supply of Cesium 133

John Galban=====N4BQ (PA28-180)

That's why I use the rubidium model :-)

"David Megginson" wrote in message
le.rogers.com...
Jim Fisher wrote:

I've always been curious about this: Wouldn't the altimeter still read
an
increase/decrease in altitude? No, the altitude would not be correct
but
for a backup to keeping the shiny side up in IMC it would have some
value,
right?

It will show the altitude you've pressurized your cabin to -- nothing to
do
with what's going on outside.

You are right, of course. So is 8000 feet a standard pressure for all
pressurized aircraft or are there some that keep 5000 or perhaps 10,000?

--
Jim Fisher

"Mike Rapoport" wrote:
How do you think your ears would feel if they only started preasurization
upon reaching 8000'?

Your ears would feel just fine. Although the climb to 8000' can
happen pretty quickly, your ears can tolerate quick decreases
in pressure much easier than quick increases. Then as the plane
climbed above 8000' the pressure inside the cabin would remain
constant so you ears would think the plane is still at 8000'.
(I believe the reason the pressure profile is not controlled
that way during ascent has more to do with the practical aspects
of the pressurizing system). Now if the same profile were
reversed on the way down, that could cause significant discomfort
esp. for those with colds or for those who can't quickly equalize
their ear pressure. A more logical profile for the cabin pressure
would be to keep the cabin effective altitude at some multiple
of the outside altitude (perhaps around 1/4). So when the plane
is at 4000 feet, your ears would think you are at 1000ft. When
the plane got up to 32000 feet, your ears (and lungs) would think
you are at 8000 feet. I don't know how the system actually works
but I'm guessing it is some approximation of what I described.
(My plane is not pressurized, so I never had to learn about
that stuff).

~Paul

My experience is different, my ears don't like climbing 3000fpm particularly
if I have a cold. Preasurization is set to a cabin altitude and a cabin
climb rate. After takeoff the outflow is restricted to maintain the desired
altitude and climb rate.

Mike
MU-2


"Paul Mennen" wrote in message
. ..
"Mike Rapoport" wrote:
How do you think your ears would feel if they only started
preasurization
upon reaching 8000'?

Your ears would feel just fine. Although the climb to 8000' can
happen pretty quickly, your ears can tolerate quick decreases
in pressure much easier than quick increases. Then as the plane
climbed above 8000' the pressure inside the cabin would remain
constant so you ears would think the plane is still at 8000'.
(I believe the reason the pressure profile is not controlled
that way during ascent has more to do with the practical aspects
of the pressurizing system). Now if the same profile were
reversed on the way down, that could cause significant discomfort
esp. for those with colds or for those who can't quickly equalize
their ear pressure. A more logical profile for the cabin pressure
would be to keep the cabin effective altitude at some multiple
of the outside altitude (perhaps around 1/4). So when the plane
is at 4000 feet, your ears would think you are at 1000ft. When
the plane got up to 32000 feet, your ears (and lungs) would think
you are at 8000 feet. I don't know how the system actually works
but I'm guessing it is some approximation of what I described.
(My plane is not pressurized, so I never had to learn about
that stuff).

~Paul

On 19-Dec-2003, "Mike Rapoport" wrote:

Preasurization is set to a cabin altitude and a cabin
climb rate. After takeoff the outflow is restricted to maintain the
desired altitude and climb rate.


Taking into account that I have never piloted a pressurized aircraft, to me
it seems like the most demanding task in managing pressurization has to be
to make sure that the cabin pressure matches the outside pressure upon
landing. If, for example, you landed at Denver with sea level cabin
pressure, you would have to sit inside the airplane for quite a few minutes
while the cabin depressurized at a comfortable rate before you could open
the door. However, most articles I've read about cabin pressure management
don't discuss this aspect. Am I missing something?
--
-Elliott Drucker

You simply set the cabin altitude to slightly above field elevation. If you
forget, the cabin pressure is dumped when the plane touches down with a loud
embarassing "whoosh" .

Mike
MU-2

wrote in message
...

On 19-Dec-2003, "Mike Rapoport" wrote:

Preasurization is set to a cabin altitude and a cabin
climb rate. After takeoff the outflow is restricted to maintain the
desired altitude and climb rate.


Taking into account that I have never piloted a pressurized aircraft, to
me
it seems like the most demanding task in managing pressurization has to be
to make sure that the cabin pressure matches the outside pressure upon
landing. If, for example, you landed at Denver with sea level cabin
pressure, you would have to sit inside the airplane for quite a few
minutes
while the cabin depressurized at a comfortable rate before you could open
the door. However, most articles I've read about cabin pressure
management
don't discuss this aspect. Am I missing something?
--
-Elliott Drucker

Mike Rapoport wrote:

How do you think your ears would feel if they only started preasurization
upon reaching 8000'?



Judging from my experience, I would be fine. But I have noticed other
people are more sensitive. I took my brother for a flight in the
Cherokee and when we leveled off at 5500 I told him we were at cruising
altitude, and he said "good, my ears will probalby stop bugging me now".
Taht surprised me, as I have never felt any ear discomfort climbing or
descending in an unpressurized GA airplane.

Do you think that a jet climbs at the same rate as your Cherokee?

Mike
MU-2


"TTA Cherokee Driver" wrote in message
...


Mike Rapoport wrote:

How do you think your ears would feel if they only started
preasurization
upon reaching 8000'?



Judging from my experience, I would be fine. But I have noticed other
people are more sensitive. I took my brother for a flight in the
Cherokee and when we leveled off at 5500 I told him we were at cruising
altitude, and he said "good, my ears will probalby stop bugging me now".
Taht surprised me, as I have never felt any ear discomfort climbing or
descending in an unpressurized GA airplane.