Originally Posted by
PDR1
It still comes down to an automation in a primary flight control which operates silently and uses only a single data source. Even Boeing know that's not the right way to design aeroplanes,
PDR
Well, in 1995 I flew a new version of the CH47 which had just such a design fault - a single data source for the altimeter. Flying along at 4000’, fortunately VMC, I became aware that we had gradually descended to more like 2000’. I informed ATC of our problem and they replied that they still had our Mode C at 4000’. Boeing (belatedly) then added a second data source. Good job we weren’t IMC, eh?