Janos Bauer wrote:
Marc Ramsey wrote:
It has nothing to do with competence. I agree with some of your
opinions, others do not.

I mean, you usually aware of the technical background (security, GPS
issues, etc-etc). On the other hand you often refuse certain suggestions
referring to existing rules and not to technical problems.

So, I must not be truly competent 8^)

Tradition is a big factor. The perceived (but not adequately studied,
in my opinion) inaccuracy of GPS altitude is another.

I also haven't really studied it but last Sunday it was the second time
when I had to fly xc without variometer and I was happy with the simple
GPS (no WAAS etc.) based palm&soaringpilot combo. I think it would be
impossible if there was really huge error (bigger than on those 20 year
old barographs).

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.

It doesn't matter how they are treated, as long as they can be
successfully calibrated within the set interval. The corrected
pressure altitudes taken from a barogram may be off by a hundred feet
or so, but they still provide a more accurate measurement of the
precise form of altitude required by the current IGC rules, than any
COTS GPS.


I don't think they are calibrated for all the temperatures.

There is no requirement that barographs be corrected for temperature.

I don't think all the mechanical impacts can be handled by calibration
(I myself (saw others do it few times) locked out the needle of one
old smoky barograph and we had to bent it back to working position,
how do you handle such an "impact"?)

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.

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 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?

Marc