That timeline on page 100 is really something. Some excerpts:
Some excerpts from the timeline on page 100:
July 8, 2015
Boeing notes its test pilot’s slow, “catastrophic” reaction time to uncommanded MCAS activation in its Coordination Sheet for the first time, saying, “A typical reaction time was observed to be approximately 4 seconds. A slow reaction time scenario (> 10 seconds) found the failure to be catastrophic due to the inability to arrest the airplane overspeed.” Boeing updated this record, citing this same information, six times from 2015 to 2018 but never shared this data with the FAA.
December 17, 2015
A Boeing AR asked in an email, “Are we vulnerable to single AOA sensor failures with the MCAS implementation or is there some checking that occurs?” In the end, MCAS was certified with a single AOA sensor and erroneous AOA data contributed to both 737 MAX accidents. Boeing is now implementing changes in the wake of both MAX crashes so that MCAS relies on two AOA sensors.
June 15, 2016
A Boeing AR Advisor emailed a colleague and asked, “What happens when we have faulty AOA or Mach number?” The colleague responds, “As for faulty AOA and/or Mach number…if they are faulty then MCAS shuts down immediately.” Faulty AOA data was a major contributing factor in both MAX crashes and MCAS did not shut down in either of those accidents.
June 16, 2016
Referring to a Boeing test pilot’s problem trimming the MAX due to repetitive MCAS activations, a Boeing engineer asks, “Is this considered a safety or cert[ification] issue?” On June 20, 2016, a colleague responds, “I don’t think this is safety, other then [sic] the pilot could fight the MCAS input and over time find themselves in a large mistrim.” This is exactly what happened on both MAX aircraft that crashed.