"Paul Bart" wrote in message ...
Recognition of this fact may have something to do with age, but the
real issues are recognizing what is to be measured,



Height above ground I would have thought. If I understand the preceding
discussion correctly, pressure altitude was used because there were no other
viable options, not because it was a good measure of height above ground.



Without any effort I can identify 3 different measurements that are
curently derived from pressure based barographs and flight recorders.
They a

continuity of flight
altitude gained following a low point
absolute altitude achieved

Height above ground is not a parameter that is used for any badge,
award, or record as far as I know.

Please don't interpret my reply as being an objection to COTS GPS.

If ever there was an opportunity to change the world from pressure
altitude to GPS altitude it was when RVSM was introduced. But no,
many aircraft faced expensive air data system retrofits because the
system was too enrenched in barometric altimetry.

Andy