An interesting article in Forbes on human error in a very unforgiving environment, i.e. treating ebola patients, and an excellent use of basic statistics to prove that cumulative risk tends to do just that, accumulate. As the number of patients being treated in the west is pretty low at the moment it also gives a good indication of just how infectious Ebola is. One might also infer that the western medical establishment is not quite so smart as it thought it was, at least when it comes to treating the big E safely.

Of course the moment of international zen in the whole story had to be the comment by the head of the CDC Dr Friedan, that and I quote “clearly there was a breach in protocol”, a perfect example of affirming the consequent. As James Reason pointed out years ago there are two ways of dealing with human error, so I guess we know where the head of the CDC stands on that question. :)


Well after a week away teaching system safety to Navy in the depths of Victoria I’m off again! Current destination, the IET’s System Safety and Cyber Security conference in Manchester.

Just to mention that if you’re coming to the workshop day I’ll be running one on safety cases, so if you’re interested drop by and pull up a chair. :)

Tenerife disaster moments after the impact

TCAS, emergent properties and risk trade-offs

There’s been some comment from various regulator’s regarding the use of Traffic Collision Avoidance System (TCAS) on the ground, experience shows that TCAS is sometimes turned on and off at the same time as the Mode S transponder. Eurocontrol doesn’t like it and is quite explicit about their dislike, ‘do not use it while taxiing’ they say, likewise the FAA also states that you should ‘minimise use on ground’. There are legitimate reasons for this dislike, having too many TCAS transponders operating within a specific area can degrade system performance as well as potentially interfering with airport ground radars. And as the FAA point out operating with the AD-B transponder on will also ensure that the aircraft is visible to ATC and other ADS-B (in) equipped aircraft (1). Which leaves us with the question, why are aircrew using TCAS on the ground? Is it because it’s just easy enough to turn on at the push back? Or is there another reason?

Continue Reading…

Interesting article on old school rail safety and lessons for the modern nuclear industry. As a somewhat ironic addendum the early nuclear industry safety studies also overlooked the risks posed by large inventories of fuel rods on site, the then assumption being that they’d be shipped off to a reprocessing facility as soon as possible, it’s hard to predict the future. :)

And in news just to hand, the first Ebola case is reported in the US. It’ll be very interesting to see what happens next, and how much transmission rate is driven by cultural and socio-economic effects…


In case anyone missed it the Ebola outbreak in Africa is now into the ‘explosive’ phase of the classic logistics growth curve, see this article from New Scientist for more details.

Here in the west we get all the rhetoric about Islamic State as an existential threat but little to nothing about the big E, even though this epidemic will undoubtedly kill more people than that bunch of crazies ever will. Ebola doesn’t hate us for who we are, but it’ll damn well kill a lot of people regardless.

Another worrying thought is that the more cases, the more generations of the disease clock over and the more chance there is for a much worse variant to emerge that’s got global legs. We’ve been gruesomely lucky to date that Ebola is so nasty, because it tends too burn out before going to far, but that can change ver quickly. This is a small world, and what happens inside a village in West Africa actually matters to people in London, Paris, Sydney or Moscow. Were I PM that’s where I’d be sending our defence force, not back into the cauldron of the Middle East…

If you were wondering why the Outliers post was, ehem, a little rough I accidentally posted an initial draft rather than the final version. I’ve now released the right one.