RBF:
Should we be coloring the altitude display red or orange for abnormal descent rates?
Given that other gauges use the green amber red, why not?
Another way to think through this is to use three different colors, so that those three are not cognatively mixed with the colors on the speed display ...
But of all the suggestions I've seen in this discussion, this one leaps out to me as "Why Didn't I Think of That?" in spades. *tips cap*