Mxsmanic wrote:

Steve Foley writes:

It's entirely possible he could give me an education on this subject, but
I'd rather go to a reliable source.

Better still, just don't depend on GPS for altitude.


Today I flew a real airplane and compared the GPS altitude from my GNS
430 with my altimeter. GPS was usually within 40' of the altimeter
which may not be the worst.

On the ground the GPS altitude was about 40' less than the GNS 430
indicated elevation of my airport but that number may be off since the
runway does slope.

Regardless, in this case GPS derived altitude was quite good.

Ron Lee