Almost a statisic

but would still be accurate at the altitude where it became blocked, and
would still increase and decrease with airspeed changes when level, the
numbers would just be meaningless, right?

kontiki wrote:
If the static line were blocked but not the pitot then the
airspeed indication would decrease with increasing altitude.

"Gary Drescher" wrote in message
...
"dlevy" wrote in message
...
I had a pitot/static problem as a new PPL (clear weather) that was very
exciting. Airspeed was fine till about 20 feet off the ground. At that
point airspeed would start dropping. I kept pushing the nose over and
airspeed kept dropping. I then realized rpm's were normal, the propellor
was attached, and everything sounded right. It scared the bejezus outta
me. Turned out to be water in the static line. Afterwards, I realized I
was way too dependant on that one indicator. Had it been IMC, it could
have been very ugly.

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.

On Wed, 12 Jan 2005 22:52:20 GMT, Matt Young
wrote:

but would still be accurate at the altitude where it became blocked, and
would still increase and decrease with airspeed changes when level, the
numbers would just be meaningless, right?


Yes! Remember, if you break the glass of the altimeter, it won't be
sealed anymore, and despite a small static error, all instruments
using static pressure will be working again (except ASI in case of
pitot failure) (doesn't work with pressurized A/C, of course!)

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.


Not really. You should remain at the same pressure altitude. If you
travel to an area with higher or lower pressure, you would be
surprised.

"dlevy" wrote in message
...
GPS groundspeed implies airspeed. If the airspeed indicator is zero,
rpm's
2500, the nose pitched up, and gps groundspeed holding at 80 knots......
which is wrong?

You see the ground moving and the altitude isn't dropping- no GPS needed

GPS groundspeed isn't really useful for aviating, since you've got to factor
wind in. 20 knots is the difference between too fast and too slow in
approach. OTOH, if you fly pitch and power settings, you won't come to grief
no matter what the wind is doing. Even IFR the GPS groundspeed isn't
necessary. If your power is too low you'll lose altitude, too high you'll
climb. I've flown complete approaches in actual IFR with a post-it over the
ASI, and never once looked at the GPS groundspeed.

So, you don't need the GPS to tell you you're moving, and it can't tell you
what your airspeed is, while pitch/power will let you fly the plane all day
long. What does GPS buy me again in this situation?

"Colin W Kingsbury" wrote in message
ink.net...
snip
GPS groundspeed is useless for flying the plane. What do you think
you're
getting by watching it?

-cwk.

"Sriram Narayan" wrote in message
news:1105574315.223629d9c9b6178c7b6b555f5ecac8c3@t eranews...

"Gary Drescher" wrote in message

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure
has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.

Oops. Yes, of course. Thanks.

--Gary

GPS groundspeed is indeed useful for aviating. You are straight and
level in IMC flying along into a 20 knot headwind at full power. Your
indicated airspeed is 70knots (80 knots true at your altitude and
pressure etc). You notice the groundspeed is 80 knots. All is well. You
get ice, and note your indicated airspeed has dropped to 50 knots. But
you note your groundspeed is 75 knots. Are you on the verge of a stall
that 50 knots indicated would tell you? Or are you still flying as
close to normal cruise?

"Doug" wrote in message
oups.com...
GPS groundspeed is indeed useful for aviating. You are straight and
level in IMC flying along into a 20 knot headwind at full power. Your
indicated airspeed is 70knots (80 knots true at your altitude and
pressure etc). You notice the groundspeed is 80 knots. All is well. You
get ice, and note your indicated airspeed has dropped to 50 knots. But
you note your groundspeed is 75 knots. Are you on the verge of a stall
that 50 knots indicated would tell you? Or are you still flying as

IIRC, the point ws in FLYING THE PLANE DURING AN EMERGENCY.

Navigating is secondary (way secondary) during the incident in question.
--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

On 12 Jan 2005 19:21:10 -0800, "Doug"
wrote:

GPS groundspeed is indeed useful for aviating. You are straight and
level in IMC flying along into a 20 knot headwind at full power. Your
indicated airspeed is 70knots (80 knots true at your altitude and
pressure etc). You notice the groundspeed is 80 knots. All is well. You
get ice, and note your indicated airspeed has dropped to 50 knots. But
you note your groundspeed is 75 knots. Are you on the verge of a stall
that 50 knots indicated would tell you? Or are you still flying as
close to normal cruise?


Or has the wind sheared?

"Sriram Narayan" wrote in message
news:1105574315.223629d9c9b6178c7b6b555f5ecac8c3@t eranews...

"Gary Drescher" wrote in message
...
"dlevy" wrote in message
...
I had a pitot/static problem as a new PPL (clear weather) that was very
exciting. Airspeed was fine till about 20 feet off the ground. At that
point airspeed would start dropping. I kept pushing the nose over and
airspeed kept dropping. I then realized rpm's were normal, the
propellor
was attached, and everything sounded right. It scared the bejezus outta
me. Turned out to be water in the static line. Afterwards, I realized I
was way too dependant on that one indicator. Had it been IMC, it could
have been very ugly.

Hm, shouldn't a blocked static line cause the airspeed indicator to show
an
increase in airspeed, rather than a decrease, with increasing altitude?


It would indicate a lower airspeed.

The pitot ram air pressure for a given airspeed decreases with higher
altitude. If the static port were blocked (at say, the takeoff altitude),
the airspeed would "indicate" a lower airspeed since the pitot pressure
has
dropped for that airspeed as the plane gains altitude. As another poster
commented, the only altitude where the ASI is accurate is at the altitude
where the blockage occurred.



Actually, the OP didn't say anything about the static line being blocked, he
said that it had water in it. The static pressure availilble at the
instruments still changes in the proper direction if the static (or pitot)
line has water in it, it just changes at a different (usually lower) rate.

Mike
MU-2
Helio Courier