Ian W, I respectfully disagree. A lot of money was at stake, riding on the MCAS being single source, hidden from virtually everyone. I am not the only one making the allegations, it's people who worked on the MAX project.
Lack of redundancies on Boeing 737 MAX system baffles some involved in developing the jet
March 26, 2019 at 5:00 pm Updated March 27, 2019 at 3:01 pm
...The design
Boeing had been exploring the construction of an all-new airplane earlier this decade. But after American Airlines began discussing orders for a new plane from Airbus in 2011, Boeing abruptly changed course, settling on the faster alternative of modifying its popular 737 into a new MAX model.
Rick Ludtke, a former Boeing engineer who worked on designing the interfaces on the MAX’s flight deck, said managers mandated that any differences from the previous 737 had to be small enough that they wouldn’t trigger the need for pilots to undergo new simulator training.
That left the team working on an old architecture and layers of different design philosophies that had piled on over the years, all to serve an international pilot community that was increasingly expecting automation.
“It’s become such a kludge, that we started to speculate and wonder whether it was safe to do the MAX,” Ludtke said.
Ludtke didn’t work directly on the MCAS, but he worked with those who did. He said that if the group had built the MCAS in a way that would depend on two sensors, and would shut the system off if one fails, he thinks the company would have needed to install an alert in the cockpit to make the pilots aware that the safety system was off.
And if that happens, Ludtke said, the pilots would potentially need training on the new alert and the underlying system. That could mean simulator time, which was off the table.
“The decision path they made with MCAS is probably the wrong one,” Ludtke said. “It shows how the airplane is a bridge too far.”
Boeing said Tuesday that the company’s internal analysis determined that relying on a single source of data was acceptable and in line with industry standards because pilots would have the ability to counteract an erroneous input.
In addition to the imminent software fix for the MCAS, people familiar with Boeing’s plans said the company now intends to make standard two features that previously were optional add-ons at extra cost.
Seattle Times:
Lack of redundancies on Boeing 737 MAX system baffles some involved in developing the jet
The bottom line is that airlines have for the most part "Aviation, Navigating, Communicating" with the 737 Classic and NG safely around the world for a long time. The AoA vane is the same part number on the NG and the MAX, yet suddenly there are two Loss Of Control accidents in a very short space of time on a new airframe due to a fault in this sensor. It is hard to conclude that a lack of aviating, navigating & communicating is suddenly the root cause of the problem.
A fully conscious rational business decision was made to withhold knowledge of the new MCAS software and down rate the risk assessment. The two accidents are proof that that an AoA failure on the MAX and the MCAS should have a failure rating of Catastrophic, and a warning feature & additional training should have been mandated as a consequence.
If that had occurred, a lot of people would still be alive, and ironically, Boeing managers and shareholders would be significantly wealthier.