Archives For ontological risk

Inspecting Tacoma Narrows (Image source: Public domain)

We don’t know what we don’t know

The Tacoma Narrows bridge stands, or rather falls, as a classic example of what happens when we run up against the limits of our knowledge. The failure of the bridge due to an as then unknown torsional aeroelastic flutter mode, which the bridge with it’s high span to width ratio was particularly vulnerable to, is almost a textbook example of ontological risk. Continue Reading…

The pentagon is functioning (Image Source: USN)

….And there are still unknown, unknowns

A while ago I posted a short piece on the difference between aleatory, epistemic and ontological uncertainty, using Don Rumsfeld’s famous news conference comments as a good introduction to the subject.

Continue Reading…

Why we risk…

15/05/2011

Why taking risk is an inherent part of the human condition

On the 6th of May 1968 Neil Armstrong stepped aboard the Lunar Lander Test Vehicle (LLTV) for a routine training mission. During the flight the vehicle went out of control and crashed with Armstrong ejecting to safety seconds before impact. Continue Reading…

The Titanic effect

27/09/2010

So why did the Titanic sink? The reason highlights the role of implicit design assumptions in complex accidents and the interaction of design with operations of safety critical systems

Continue Reading...

One of the traditional approaches to reducing risk is to work on reducing the severity (S) of an accident rather than reducing the Likelihood (L) of occurrence. As the classical definition of risk is, Risk (R) = L X S, by reducing S we reduce the risk. Simple really… Continue Reading…

So far as we know flight AF 447 fell out of the sky with its systems performing as their designers had specified, if not how they expected, right up-to the point that it impacted the surface of the ocean.

So how is it possible that incorrect air data could simultaneously cause upsets in aircraft functions as disparate as engine thrust management, flight law protection and traffic avoidance?

Continue Reading...

In one’s professional life there are certain critical works that open your eyes to how lucidly a technical argument can be stated. Continue Reading…