Ron Rosenfeld wrote:

I did not see that article, and cannot locate it just now. But I don't
understand the logic that would imply that for a TSO146 GPS unit.

Can you elaborate?

Well, I found that one and couldn't find the reference I thought I read. But I
did find another article that contained this "Currently, two manufacturers of GA
avionics — UPSAT and Chelton — have WAAS-certified receivers that can be used
for 'sole-source' IFR navigation, meaning no other navigation systems are
required on the aircraft. UPSAT expects to receive certification for vertical
navigation ('glideslope') within two months. Other manufacturers will be
offering WAAS receivers soon." That states I was wrong.

George Patterson
The desire for safety stands against every great and noble enterprise.