Cecil Chapman wrote:

BUT,,, IF I have the carb heat on full and I still
manage to ice-up, now I am in a condition that allow me few options to
address - there is no other fall back at that point.

If you're in conditions where full carb-heat won't prevent carb-ice, what
difference does it make whether you learn that full carb-heat is
insufficient quickly or slowly?

Is there something I'm missing? Is the second scenario I'm describing
impossible? I'd be curious about your thoughts.

That's why I asked whether NW had the heat hot when descending (and never
saw an answer, sadly). I've never had a situation where carb-ice formed
despite the heat being on. But that doesn't preclude the possibility (esp.
since I'm in a very different neighborhood).

I've only recently started flying aircraft that have carb-temp gauges. You
can bet I'll be watching those with some curiosity.

- Andrew