Mode C Altitude Q - no Kalisman Correction? (Barometric Pressuredeviation correction?)

"Cockpit Colin" wrote in message
...

In our neck of the woods (NZ) they only apply a correction below the
transition altitude - no need for any correction for flight levels.

Assume it's the same in the states


It's the same everywhere. It can be no other way.

Steven P. McNicoll wrote:

It's the same everywhere. It can be no other way.

Of course it could. Whether it would make sense is a different question.

Stefan

"Stefan" wrote in message
...

Of course it could. Whether it would make sense is a different question.


How could it be any other way?

Steven P. McNicoll wrote:

How could it be any other way?

Just a few examples: It could be QNH everywhere (requires defined QNH
regions). It could be GPS altitude (would even simplify things a lot,
but requires all aircraft to be expensively equipped). Heck, it could
even be radar altitude everywhere, of course compensated for ground
elevation. As I said, whether it would make sense or even be practical
is a different question, but there are a lot of solutions which are
thinkable.

Stefan

"Stefan" wrote in message
...

Just a few examples: It could be QNH everywhere (requires defined QNH
regions).


If it's QNH everywhere there's no transition altitude.



It could be GPS altitude (would even simplify things a lot, but requires
all aircraft to be expensively equipped). Heck, it could even be radar
altitude everywhere, of course compensated for ground elevation. As I
said, whether it would make sense or even be practical is a different
question, but there are a lot of solutions which are thinkable.


How does one set the barometric pressure for GPS altitude or radar altitude?

Steven P. McNicoll wrote:

If it's QNH everywhere there's no transition altitude.
....

Right.

As I understood, you said: This is the only way to set the altimeter. I
answered: No, there are a myriade of ways to do it, from which one was
chosen, probably for good reasons.

Maybe I misunderstood your first statement.

Stefan

"Stefan" wrote in message
...

Right.

As I understood, you said: This is the only way to set the altimeter. I
answered: No, there are a myriade of ways to do it, from which one was
chosen, probably for good reasons.

Maybe I misunderstood your first statement.


I was responding to Cockpit Colin's message on how things are done in New
Zealand. He said a correction for barometric pressure is applied only below
the transition altitude, and that there's no need for any correction for
flight levels. He assumed it's the same way in the US. I said it's the
same way everywhere, as the definitions of "transition altitude" and "flight
level" require it to be that way.

"Steven P. McNicoll" wrote in message
ink.net...

"Stefan" wrote in message
...

Right.

As I understood, you said: This is the only way to set the altimeter. I
answered: No, there are a myriade of ways to do it, from which one was
chosen, probably for good reasons.

Maybe I misunderstood your first statement.


I was responding to Cockpit Colin's message on how things are done in New
Zealand. He said a correction for barometric pressure is applied only
below the transition altitude, and that there's no need for any correction
for flight levels. He assumed it's the same way in the US. I said it's
the same way everywhere, as the definitions of "transition altitude" and
"flight level" require it to be that way.

For example in the UK, transition level tends to be 3000 ft except around
the major airports where it can be as high as 6000ft. This means that the
lowest FL is usually FL035.

The normal practice is to take off on the airfieldQNH, and then if on a
cross country trip, readjust the setting to the Regional QNH. This is the
lowest forecast QNH for the respective region.

On arrival at an airfield we set QFE which gives zero elevation when
landed.

Only IFR traffic is obliged to use flight levels above 3000ft or the
transition altitude (in fact one of the definitions of IFR is the use of
flight levels). VFR traffic can use then if they want but then should follow
Instrument flight Rules.

cb