Marc Ramsey wrote:

You are comparing apples to oranges. GPS measures geometric altitude
with a typical error of, say, +/- 50 feet. Barographs measure
calibrated pressure altitude with a typical error of, say, +/- 50 feet.
GPS altitude can not be corrected to pressure altitude with reasonable
error bounds, unless specific meteorological data is provided for the
time and place of the flight. Pressure altitude can not be corrected to
geometric altitude with reasonable error bounds, unless specific
meteorological data is provided for the time and place of the flight.
Without making these meteorological corrections, geometric and
calibrated pressure altitude can differ by as much as 1000 feet for a
Diamond altitude gain.

The whole altitude task is about the ability to gain certain amount of
energy from air (thermal, wave, something else). For me it's a geometric
issue. If someone is able to get from A to B and the altitude difference
is more than X than it's fine. Not the air pressure at that altitude
qualifies the pilot.
You already agree with it so what do we argue about?

I don't think they are calibrated for all the temperatures.
There is no requirement that barographs be corrected for temperature.

Hmm, those thin metal plates and other small parts could behave quite
differently at +40C than -40C (typical wave temperature at my country).

That barograph should have been marked as potentially faulty. An OO, if
aware of this, should refuse to certify a flight using it until it is
repaired and recalibrated.

Should.

And the most important issue, what I stated
befo neither barographs nor cameras are sealed by OO on most of the
places I visited...


The Sporting Code requires sealing the barograph, but not necessarily
the cameras (SC3 4.6.3, 4.7.2). If an OO is unable to follow these
simple rules, how likely is it that he/she will follow the more
technically complex procedures that might be required for a COTS GPS?

No they won't.

No one wants to cheat with them, it's just the way things going on
some (maybe most) places.


I've seen similar things. Given this, the obvious solution would be to
award badges using the honor system. If this is not acceptable, then
some level of procedural and/or technical security measures must be in
the rules (even if some do not follow them). How much security is enough?

I would accept any trace file and a sign from the OO. Yes, from the
same OO who doesn't seal the barograph. It's the same level of security
as the current barograph+photo process.

/Janos