Andrew Gideon wrote:
Michael wrote:

First off, with dual AI's next to each other, I believe that following
a dying AI into an unusual attitude becomes far less likely, and thus
while the chances of recovery from the unusual attitude are reduced
slightly, the chances of encountering it in the first place are reduced
dramatically. Not so with a backup vacuum - you have to engage it.

This is the first of my two major reasons for preferring the backup AI. It
helps with problem detection. A backup vacuum doesn't.

Which is why the Precise Flight standby systems include a low-vacuum
annunciator light.

-cwk.