Originally Posted by
tdracer
A longer, more thorough review and vetting of the design may have pointed out the flaw in using a single sensor. The problem with MCAS was that in the rush to get things certified, no one considered the impact of a cascade of warnings and faults associated with a bad AoA sensor - overwhelming the flight crew and resulting in them failing to appreciate what was happening with the stab trim.
They had 30+ years to understand the effect of a false stall warning. No one inside or outside the company spotted that problem. No one considered that no one had made a useful definition of "runaway trim" in those same 30+ years, even though the switches provided to deal with it were there the entire time. 100 years would not have been enough to notice that pilots might not recognize runaway trim and would not realize what a false stall warning was like. We know that because Airbus was unable to communicate a similar problem with the pilots of AF447.
The problem wasn't in using a single sensor. The problem was that the system reporting that single sensor was unable to validate it. Had the SMYD system been properly designed the AoA sensor would have been invalidated, causing the back-up sensor to be used and no false stall warning issued. The Lion Air miscalibration was also not identified as a potential problem - if it had been then an on-aircraft verification would be required. The Ethiopian sudden move to 70 degrees should have seen that sensor taken out of the loop; a better design would have had a vane stop at 60 degrees AoA so that 70 would have indicated out-of-range. Again, 30+ years and no one noticed.
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I find odd the calls for a massive new redesign effort for an entirely new airframe with hundreds of thousands to millions of fundamental decisions to be made by the same group that is having trouble with the thousands of new decisions they need to make about an existing product.
In IBM, when IBM meant something, they used to have a group called the Black Team. This was a core of independent reviewers with significant experience that was given the freedom to go where they wanted and investigate what they wanted. A bit like the Spanish Inquisition, but less physical torture. They questioned fundamental assumptions, examined processes, and ran roughshod over the unprepared. In the initial rise of Microsoft, Bill Gates performed that function with the OS and the applications teams. It requires people who are smart enough to do the entire design job, but simply don't have the hours to do so. The clear mission isn't to tear people to bits, but to make the product as perfect as possible. Passing an audit was seen as a positive accomplishment.
This process made IBM an industrial giant and a feared competitor. It took the US Government to cripple them enough to allow Microsoft to take their place.