[SystemSafety] Correctness by Construction

[Peter Bernard Ladkin]

On 2020-07-10 12:24 , Dewi Daniels wrote:
> 
> There is no evidence that the MCAS software failed to satisfy its requirements. It appears that the
> MCAS software behaved correctly according to its requirements, but that those requirements specified
> unsafe behaviour. It seems that the system safety engineers and the requirements engineers only
> considered a single activation of MCAS. They do not appear to have considered the possibility that
> MCAS could activate repeatedly, eventually driving the stabilizer to a fully nose down position.

The Congressional report also makes it clear that the company also altered the activation conditions
of the (sub)system (which Boeing still calls a "function" of the STS), without either revisiting the
hazard/risk analysis or informing the regulator.

PBL

Prof. Peter Bernard Ladkin, Bielefeld, Germany
Styelfy Bleibgsnd
Tel+msg +49 (0)521 880 7319  www.rvs-bi.de





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