A question I would like to see settled, important for those who fly
beneath controlled airspace (CAS), is how to ensure that the CAS has
not been entered. (In the UK at least, this is treated as a reason to
not grant claims.)

If the base of CAS is defined by flight level, GPS altitude does not
establish whether or not CAS was violated unless some elaborate
computations are done, AIUI. Baro is needed.

If CAS is defined by height or altitude, GPS may suffice.

As our moving map software is using height/altitude data for glide
angle to goal etc., can it mislead people to think that they are clear
of CAS when on fact just up inside it?

If the logger is the source of the GPS engine for the moving map, this
seems to me to be an issue.

I was recently in a comp where one pilot on successive days was
penalised for just slightly going up into CAS. He did not mean to. I
suspect that the FL/Altitude difference may have played a part.

Chris N.