If you are redesigning the panel on a the HP-24 that is already certificated
you "may need to" look at the original certification papers and see what is
required or stated for certification. You will need to meet the original
certification requirements.

If the Tasman data module reports pressure altitude and can be adjusted
based on local altimeter settings like a standard altimeter.. a dial
altimeter may not be required. But.. will it still work if you loose
electrical power? Best to put in a small diameter mechanical altimeter as a
back up. You'll have a mechanical vario as a back up in case of electrical
problems won't you? Why not an altimeter.

BT


"Brad" wrote in message
...
I am in the process of designing the instrument panel/layout for my
HP-24. Still a ways to go before I will need it, but it is raining out
and my CAD program is running and so is my
imagination..........so.............I was reading about the new Tasman
Data Module on Paul R's website and see that it provides pressure
altitude.

I will be using a GPS to run my PDA, that gives GPS altitude, if I use
the Tasman vario and data-module package, would I really need a dial
altimeter?

Thanks,
Brad