Originally Posted by
GordonR_Cape
It is deeply ironic that the issue MCAS was designed to cater for was never flight critical, and might never have occurred during the lifetime of the aircraft. Instead the fix ended up killing hundreds of people.
This highlights the underlying issue that the industry has processes that can bite back. To achieve compliance with a particular rule a simple fix is implemented, and that has a potential for unintended consequences. The failure mode of the compliance fix has it's own unknown interaction with the operating system at the man machine interface; somewhere along the way recognition failed as to the underlying cause, for a crew that had never heard of the "fix" and to another crew that had learnt of the problem due to the revelations of the first crews misfortune. In fact, the knowledge gained in the flight preceding JT610 was lost on the next crew as well, the system doesn't allow for the timely transfer of information, and it probably cannot do so under any process that validates the information and the output to avoid errant information being introduced.
The constant offset once in motion would appear inconsistent with a loss of the sin or cos output alone as far as I understand the use of those functions to derive the A-D output state. Contend as previously commented that the sensor itself is unlikely to be the component that has the fault, which leads to the install, wiring, or processing of the signal as being the point of failure. The loss of a single resolved output is intriguing, giving an erroneous result but it would appear that the offset error would alter with the change of actual AOA. The aircraft was operated from low speed, through to high speed, with substantial change in actual AOA, but the offset appears to be constant.