Originally Posted by
GordonR_Cape
An important point not often discussed, was whether any of those other systems were operating at the same time as MCAS and stick shaker.
In the Lion Air preliminary accident reports, illumination of the FEEL DIFF PRESS warning was cited in the maintenance history, and the post-Lion Air emergency AD includes it as a symptom of the failed AOA. This would be an indication of the Elevator Feel Shift Module activation. The STS would not have been active with flaps up. We know about the stick shaker and MCAS. There are no published DFDR traces for Leading Edge Device position, so we don't know for sure if the Autoslats system was active, but hopefully that information will be included in future updates. The Ethiopian preliminary and at least one incident report I found in the Aviation Safety Reporting System database describes the presence of small yaw oscillations which would be expected if the yaw damper response was suppressed.