Originally Posted by
retired guy
What alarms me here is that there are people here, and especially that long Dutch report that do seek to remove a lot of the responsibility onto a Rad Alt failure and away from a failure of the crew to monitor IAS and apply power manually the moment it fell
below V Ref. Never mind ignoring several blindingly obvious stall warnings culminating in stick shake and I imagine airframe buffet.
I hope I am not speaking only for myself when I say that I am not seeking to devolve all, or even the majority of, the responsibility onto a Rad Alt failure. It is but one of the 'holes in the Swiss Cheese' that lined up on this occasion. It is, however, for designers and engineers (and many others) to remove as many holes
as is reasonably possible, and having the autothrottle depend on a single Rad Alt and not swap sides with the FMC, or indeed have a separate manual switch (which would affect certification) is a decision that seems to require justification.
I certainly regard good airmanship as valuable, and share with you considerable disquiet at the failure of the crew to monitor IAS. Automation should be a supplement to airmanship, not a replacement. Putting pilots in the invidious position of needing to understand the 'state' of the automation better than the aircraft understands itself really should not be allowed; yet pilots are expected to diagnose subtle failures in automation in the absence of full information, under time pressure. It is no wonder that some don't succeed. Pilots are human, and putting humans into safety-critical control loops with incomplete or inaccurate information will result in failures. Helpful automation should reduce the numbers of such failures.