C J Campbell wrote:
Newer vacuum AIs have warning flags, dual vacuum pumps, and vacuum warning
lights on the annunciator panel. If I had an electric AI and a vacuum AI and
they disagreed markedly, I would be suspicious of the one having warning
lights and flags all over it.

CJ,

How do newer vacuum AIs come with dual vacuum pumps?

We have a "warning flag" on our newer AI. I note that it is really
a low vacuum flag. It doesn't say a thing about how reliably the
instrument itself is operating.

Sydney