I was cleaning out my (metaphorical) sock drawer and came across this rough guide to the workings of the Australian Defence standard on software safety DEF(AUST) 5679. The guide was written around 2006 for Issue 1 of the standard, although many of the issues it discussed persisted into Issue 2, which hit the streets in 2008.

DEF (AUST) 5679 is an interesting standard, one can see that the authors, Tony Cant amongst them, put a lot of thought into the methodology behind the standard, unfortunately it’s suffered from a failure to achieve large scale adoption and usage.

So here’s my thoughts at the time on how to actually use the standard to best advantage, I also threw in some concepts on how to deal with xOTS components within the DEF (AUST) 5679 framework.

Enjoy :)

Indonesian AirNav radar screenshot (Image source: Aviation Herald)

So what did happen? 

While the media ‘knows’ that the aircraft climbed steeply before rapidly descending, we should remember that this supposition relies on the self reported altitude and speed of the aircraft. So we should be cautious about presuming that what we see on a radar screen is actually what happened to the aircraft. There are of course also disturbing similarities to the circumstances in which Air France AF447 was lost, yet at this moment all they are are similarities. One things for sure though, there’ll be little sleep in Toulouse until the FDRs are recovered.

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OK, so it’s over, and it could have been worse

So what have we learned from all this? Well let’s start with the basics. This was a small event, in comparison 9/11 killed more than 3,000 people, while the Bali bombings killed 202. In fact today was not even close to the Sarin gas attacks in Japan which killed 5 people and severely injured 50 more.  So in the scheme of things this is small beer.

And as oft turns out it was carried out by someone who was fundamentally crazy plus stupid. Contrary to what Hollywood, politicians and the security industry espouse most terrorists are inept, and most terrorist schemes fizzle out.

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My favourite line, “Engaging the sleigh in a dive is forbidden under all circumstances… children expect to hear sleigh bells, not a Stuka diving horn”. Click on the cover to read the whole manual.

Sleigh Pilot Notes (Image source: Air Council)

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Or how do we measure the unknown?

The problem is that as our understanding and control of known risks increases, the remaining risk in any system become increasingly dominated by  the ‘unknown‘. The higher the integrity of our systems the more uncertainty we have over the unknown and unknowable residual risk. What we need is a way to measure, express and reason about such deep uncertainty, and I don’t mean tools like Pascalian calculus or Bayesian prior belief structures, but a way to measure and judge ontological uncertainty.

Even if we can’t measure ontological uncertainty directly perhaps there are indirect measures? Perhaps there’s a way to infer something from the platonic shadow that such uncertainty casts on the wall, so to speak. Nassim Taleb would say no, the unknowability of such events is the central thesis of his Ludic Fallacy after all. But I still think it’s worthwhile exploring, because while he might be right, he may also be wrong.

*With apologies to Nassim Taleb.

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Boeing 787-8 N787BA cockpit (Image source: Alex Beltyukov CC BY-SA 3.0)

The Dreamliner and the Network

Big complicated technologies are rarely (perhaps never) developed by one organisation. Instead they’re a patchwork quilt of individual systems which are developed by domain experts, with the whole being stitched together by a single authority/agency. This practice is nothing new, it’s been around since the earliest days of the cybernetic era, it’s a classic tool that organisations and engineers use to deal with industrial scale design tasks (1). But what is different is that we no longer design systems, and systems of systems, as loose federations of entities. We now think of and design our systems as networks, and thus our system of systems have become a ‘network of networks’ that exhibit much greater degrees of interdependence.

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In by the out door