Tony Burton wrote:
Marc, it occurs to me that this may not necessarily be so as long as the
IGC rules for FRs don't have to change in order to introduce a specific
COTS GPS. For example, each FR approved by the the GFAC comes with an
"approval document" which delineates how that FR must be used, OO actions,
etc.

So, say that some Garmin GPS is ICG-compliant except for the barograph
function. Could not such an FR be approved by the IGC GFAC committee with
the restriction in its approval document that it could not be used for
height evidence?

No, since pressure altitude recording capability is a non-optional
requirement of the Technical Specification (see sections 2.4 and 2.6.5).
In any case, I believe all FAI badge-related flight performances
require altitude evidence, with the sole exception of the 5 hour
Silver/Gold duration.

Marc