Only blip there, Mac, is that if you look at the PGF Airbus accident, 2 of the 3 ADRs were giving apparently 'normal' readings (having frozen in the cruise) while the third was giving correct and significant readings and warnings but all 3 were 'shut-off' by the logic. There's your software dilemma. Presumably some nice little nurse comes along in your scenario and ideally makes a logical assumption, but in mine along she comes to find all three readings blank.