Altimeter inaccurate

"Ron Rosenfeld" wrote in message =
...
On Mon, 03 May 2004 02:40:18 GMT, Judah wrote:
=20
It begs an interesting question, though...

If an IAP is based on object clearance (in some cases, as low as 100' =

clearance, right?), but does not account for temperature variations =
and=20
does not actually measure geometric altitude above the ground, is it =
not=20
possible that one would find oneself at an altitude that from a=20
barometric standpoint is legal and correct, but from a geometric =
altitude=20
is within the bounds of that tower that would have been 100' lower if =
it=20
also changed altitude with the temperature?
=20
It is my understanding that in Canada there is a requirement to alter
minimums for certain approaches in very cold weather. No such =
requirement
exists (Part 91, at least) in the US.
=20
I don't believe there have been any accidents in the US due to this
phenomenon.
=20
Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

Along that line, perhaps you've noticed that the new VNAV approaches
typically carry a note to the effect that Baro-VNAV is not authorized
at temperatures below some limiting number.
---JRC---

On Mon, 03 May 2004 20:34:22 GMT, "John R. Copeland"
wrote:

Along that line, perhaps you've noticed that the new VNAV approaches
typically carry a note to the effect that Baro-VNAV is not authorized
at temperatures below some limiting number.
---JRC---

Yes, I have. The RNAV (GPS) Z RWY 1 at KPQI states Baro-VNAV not
authorized below -16°C (4°F).


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)