On Thursday, December 14, 2017 at 5:00:23 PM UTC-5, John Foster wrote:
Why do so many gliders seem to have multiple varios? Is it that critical to have a back-up for this instrument? Do they often fail and leave you in "
the lurch"?

I have a mechanical vario as a second because it will get me home if I have a complete electrical failure. That and a chart is all I need to get back.
And yes it has happened.
UH