On Thursday, December 14, 2017 at 4:00:23 PM UTC-6, 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"?

Maybe I'm missing something, but it looks like nobody in this thread has mentioned the advantage - once you have more than one vario - of different scale ranges. I can remember most of our club gliders had two varios: one up to 5m/s and the other one up to 10 or 30 m/s.