Mike Borgelt wrote:
I believe that was calculated before SA was turned off. As I pointed
out above I doubt very much that any cockpit static can be better
than 50 to 100 feet.Static ports on gliders are sometimes pretty
terrible too so may not be any better. Try a good side slip and see
what happens also.
Add in the other error sources and you are worse than GPS altitude at
any altitude much above 1000 feet AGL.

It isn't a question of accuracy, it's a question of what is being
measured. Some believe we should continue to measure pressure altitude,
simply because that's what we've always done. I think it safe to say
that is now recognized by the IGC that once you get into the tropopause,
the magnitude of the error goes up rapidly. The current world altitude
records can't really be said to measure altitude, they simply measure
record low pressures.

Then again neither the original reasoning nor the persuasion seems to
have seen the light of day.

Frankly, GFAC is pretty much like every other committee I've been
involved with. Decisions aren't necessarily made by reason or
persuasion, they often are made by something approximating the consensus
when everyone gets tired of discussing it. After a few years, it's
often difficult to figure out exactly why a particular decision was made.

Keep in mind, there is no secretary, no meeting notes. Just a few
people spread out over a couple of time zones, many of whom have never
met any of the others face to face. 95% of the communication that goes
on is over email, and there's is no central archive. Perhaps if there
was a more sizable budget and actual salaries, we could communicate to
all with the level of detail and consistency you seem to be expecting.
But, for the moment you are stuck with a bunch of volunteers, some of
whom have been putting up with this sort of grief for 10 years now.

Do you realise that the original requirement drove some serious system
architecture considerations for manufacturers? As I said the GFAC were
originally adamant about no static connections - what changed their
minds?

Yes I do realize that. Just as I'm sure you realize that the concept of
flight recorders was very new in 1995, and that there has been a steep
learning curve for all involved. You also realize that the makeup of
GFAC now is quite different than it was in 1995. And, of course you are
fully aware that people can change their attitudes about issues over time.

How does anyone trust the rules when they may change next week?

The rules don't change every week. Rule changes are proposed at the IGC
meeting each March. Those rule changes that are accepted at the meeting
go into effect the following October. The manufacturers of approved
flight recorders (and those who have notified us that they intend to
submit a recorder for approval) are nearly always given advanced
notification (nobody is perfect, except you apparently) of proposed
changes, and asked for their input.

Nothing I've seen written here convinces me that anyone on GFAC has a
clue.

Well, at least we don't sit around badmouthing you on r.a.s.

Marc