The QF 72 accident illustrates the significant effects that ‘small field’ decisions can have on overall system safety.
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How do ya do and shake hands, shake hands, shake hands. How do ya do and shake hands and state your name and business… Tweedle Dum & Dee (Through the Looking Glass)Lewis Carrol
Yes Alice, Some folk still believe in N Versioning
You would have thought after the Leveson and Knights experiments that the theory that independently written software would only contain independent faults was dead and buried.
Another beautiful theory shot down by hard cold fact. Unfortunately like conspiracy theories the theory of n-versioning keeps on keeping on (1).
Now this would be of only passing interests if it weren’t for the fact that engineers actually continue to build systems that relay on what is effectively pseudo-scientific gibberish (2).
I was cleaning up some of my work and came across this copy of the board of investigation report into the Ariane 501 accident. I’ve added my own personal observations as well as those of other commentators to the report. What I find interesting about this accident, is the role that untested and incorrect assumptions (i.e. a faulty fault hypothesis) played in ESA’s selection of a particular system architecture. This faulty hypothesis also blinded ESA to the risk of common cause software faults.
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Recent incidents involving Airbus aircraft have again focused attention on Airbus’ approach to cockpit automation and it’s interaction with the crew.
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While some commentators have taken the last message received from AF 447 to indicate that the aircraft had suffered a major structural failure and was decompressing all we really know is that at that point in the event sequence there was a rapid change in reported cabin altitude.
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The DO-178 Software Development Standard and the B-777 9M-MRG Incident
In August 2005 a Boeing 777 experienced an in-flight upset caused by the aircraft’s Air Data Inertial Reference Unit (ADIRU), generating erroneous acceleration data. The software fault that caused this upset points to flaws in the DO-178 software development process. Continue Reading…
The statement by, AirBus regarding the robustness of the AirBus AOA voting logic disclosed in the ATSB QF72 accident report raises some interesting questions as to what was actually meant by the term robustness.
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