Originally Posted by
Discorde
Adjusting GPS altitude to match indicated barometric altitude would be accomplished electronically within the apparatus without pilot input required.
And just how long and how much money would it take for the CAA to certify and approve such an electronic system?
You can go to a shop today and buy a Casio wristwatch which will display your altitude, but I don't think the CAA would accept that in lieu of a barometric altimeter.