[SystemSafety] US House Transportation Committee Preliminary Report into Boeing 737 MAX

[Peter Bernard Ladkin]

... development, certification and response to the accidents is scathing, both concerning Boeing and
concerning the FAA. A short review is at

https://www.theguardian.com/business/2020/mar/06/boeing-culture-concealment-fatal-737-max-crashes-report

The 13pp report is nominally available from
https://transportation.house.gov/news/press-releases/nearly-one-year-after-launching-its-boeing-737-max-investigation-house-transportation-committee-issues-preliminary-investigative-findings-

but I get an Error 404 when trying. Google, however, finds it quickly:

https://transportation.house.gov/imo/media/doc/TI%20Preliminary%20Investigative%20Findings%20Boeing%20737%20MAX%20March%202020.pdf


The committee evaluated some 600,000 pages of documents and of course has seen and read things that
have not yet made it into the public domain. There are a number of facts of which I was not yet
aware. Here is a selection of what I consider to be system-safety highlights.

MCAS was deliberately described as a "new function" of the STS rather than a new system, with an AR
concurring, "to avoid greater FAA certification requirements and pilot training impacts on the 737
MAX program" (Footnote 16).

"Early on" in development (p9, substantiated in Footnote 46), Boeing was aware that if pilots did
not respond (appropriately) within 10 seconds to a "runaway stabiliser" condition caused by MCAS
activation, the severity is "catastrophic". Multiple Boeing ARs were aware of this, but it was never
reported to the FAA. This is for me new.

In 2015, an AR raised the issue of whether the AC was "vulnerable to single AOA sensor failures...."
 The answer is yes (obviously), and the aircraft was delivered with this vulnerability. (p7)

In 2016, redesign of the activation conditions of MCAS did not lead to safety reevaluation (p7).

Concerning the "AOA Disagree" alert, Boeing has apparently publicly blamed its SW supplier. However,
the SW was accepted and verified by Boeing in this configuration in May 2015 (p8). Boeing knew the
alert was not functioning in August 2017, three months after the aircraft entered revenue service,
and complained to the supplier (p8). "The Committee also discovered that one AR who was aware that
Boeing knowingly delivered aircraft with inoperable AOA Disagree alerts to its customers took no
action to inform the FAA" (p4). "Although the AOA Disagree alert was not a safety-critical
component, Boeing knowingly delivered 737 MAX aircraft to its customers that did not conform to the
airplane’s type certificate, and the FAA has failed to take any measures to hold Boeing accountable
for these actions." (p9)

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
MoreInCommon
Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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