On Thu, 03 Jun 2004 13:52:29 GMT, "Paul Bart"
wrote:


"Marc Ramsey" wrote in message
.com...
Paul Bart wrote:
However given the assertion that the pressure altitude can differ
by as much as 1000ft from the geometric altitude, does it imply that two
pressure altitudes can actually differ by 2000ft? Would it not provide
sufficient argument to switch to geometric altitude?

Yes, this is correct. You don't have to climb as high on a cold winter
day, as you would on a hot summer day, to obtain a specific pressure
altitude gain. But, I suspect some (maybe most?) would say that we have
always measured pressure altitude is this sport, and that we should
continue doing so...

Marc

Hi Marc

Thanks for your reply. Given the budding status of my gliding career, this
is not likely to be an issue for me any time soon , however given that GPS
can *potentially* reduce an error, by up to 1000 ft it should be seriously
considered. I wonder if the resistance to change is mainly due to the high
average age of the gliding fraternity?


I have a strong suspicion that climbing to a pressure altitude should
present much the same difficulty regardless of which way it differs
from the geometric altitude, but climbing to a geometric altitude will
get easier as the pressure (and hence pressure altitude) rises.

Unless I'm much mistaken, this could be used as an argument for
retaining the pressure altitude for badges.

What have I missed or misunderstood here?

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :