Setting altimeters with no radio

Since it is possible to fly without voice radio equipment, and given
that (if I understand correctly) pilots are supposed to have their
altimeters set correctly to a reference located not more than 100
miles from their position, how does an aircraft without a radio keep
its altimeter properly set as it travels?

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Mxsmanic wrote:
Since it is possible to fly without voice radio equipment, and given
that (if I understand correctly) pilots are supposed to have their
altimeters set correctly to a reference located not more than 100
miles from their position, how does an aircraft without a radio keep
its altimeter properly set as it travels?


For VFR, an adjustable altimeter is not required. Therefore, such
a 100 mile rule doesn't exist.

F--

TxSrv writes:

For VFR, an adjustable altimeter is not required. Therefore, such
a 100 mile rule doesn't exist.

OK. But in that case how do VFR flights maintain specific altitudes?

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"TxSrv" wrote in message
. ..

For VFR, an adjustable altimeter is not required. Therefore, such a 100
mile rule doesn't exist.


What aircraft altimeter is not adjustable? IFR flight requires a sensitive
altimeter adjustable for barometric pressure, VFR flight simply requires an
altimeter. But even altimeters that cannot be adjusted for barometric
pressure are adjustable. My Champ' came with a single-needle altimeter,
once around the dial was 10,000 feet. I hated it, the needle never seemed
to move. But there was an adjustment knob that rotated the dial so the
needle would point to field elevation.

The regulation requires aircraft without radios to set the altimeter to the
elevation of the departure airport or an appropriate altimeter setting
available before departure.

you cant

"Mxsmanic" wrote in message
...
Since it is possible to fly without voice radio equipment, and given
that (if I understand correctly) pilots are supposed to have their
altimeters set correctly to a reference located not more than 100
miles from their position, how does an aircraft without a radio keep
its altimeter properly set as it travels?

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GPS, even a $100 hikers model will solve the problem. But I
just say, look at the ground, you can judge 1,000 feet
pretty well and you only need to apply the hemisphere rule
above 3,000 AGL.


"BT" wrote in message
...
| you cant
|
| "Mxsmanic" wrote in message
| ...
| Since it is possible to fly without voice radio
equipment, and given
| that (if I understand correctly) pilots are supposed to
have their
| altimeters set correctly to a reference located not more
than 100
| miles from their position, how does an aircraft without
a radio keep
| its altimeter properly set as it travels?
|
| --
| Transpose mxsmanic and gmail to reach me by e-mail.
|
|

"Jim Macklin" wrote in message
...
GPS, even a $100 hikers model will solve the problem.

No, it won't.

they give altitude, accurate to within a few feet. just set
the altimeter to read the same. then you know adjusted
pressure. considering the legal requirements, it is
perfectly adequate.

see http://mtp.jpl.nasa.gov/notes/altitude/altitude.html



"Peter Duniho" wrote in
message ...
| "Jim Macklin" wrote
in message
| ...
| GPS, even a $100 hikers model will solve the problem.
|
| No, it won't.
|
|

Jim Macklin schrieb:
they give altitude, accurate to within a few feet. just set
the altimeter to read the same.

NO, dont' do this. The whole aviation system (airspace, separation...)
is based on pressure altitude, not geometric altitude.

Stefan

"Jim Macklin" writes:

they give altitude, accurate to within a few feet.

Unfortunately, no, they do not. GPS is accurate for lateral
navigation, not vertical navigation. GPS altitudes can easily be off
by as much as 200 feet at ground level in comparison to a correctly
set altimeter, and at altitude the disparity can reach 500 feet.

The reason for this is that the angles used for triangulation of
lateral positions are large and permit a high level of precision, but
the angles for triangulation of altitude are very small and it's very
easy to be off by a wide margin. GPS was designed to measure lateral
positions accurately, but it performs poorly for altitude. It is
typically much less accurate than an altimeter for altitude, and the
computed altitude constantly changes (significantly) as the satellites
move, in a way that is, for aviation purposes, practically random.

... just set the altimeter to read the same.

This is a good way to fly into a mountain, or another aircraft, or the
runway.

... then you know adjusted
pressure. considering the legal requirements, it is
perfectly adequate.

No, it is not. It's especially dangerous for RVSM flight, but it's so
inaccurate that it should never be used for anything, except as a last
resort (if the altimeters disintegrate, or whatever).

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