For those of you interested in such things, there’s an interesting thread running over on the Safety Critical Mail List at Bielefeld on software failure. Sparked off by Peter Ladkin’s post over on Abnormal Distribution on the same subject. Whether software can be said to fail and whether you can use the term reliability to describe it is one of those strange attractors about which the list tends to orbit. An interesting discussion, although at times I did think we were playing a variant of Wittgenstein’s definition game.

And my opinion? Glad you asked.

Yes of course software fails. That it’s failure is not the same as the pseudo-random failure that we posit to hardware components is neither here nor there. Continue Reading…

The reasonable person is not any particular person or an average person… The reasonable person looks before he leaps, never pets a strange dog, waits for the airplane to come to a complete stop at the gate before unbuckling his seatbelt, and otherwise engages in the type of cautious conduct that annoys the rest of us… “This excellent but odious character stands like a monument in our courts of justice, vainly appealing to his fellow citizens to order their lives after his own example.”

J.M. Feinman, on the reasonable person (2010)

It is better to be vaguely right than exactly wrong

Carveth Read (1898) Logic, deductive and inductive

SR-71 flight instruments (Image source: triddle)

How a invention that flew on the SR-71 could help commercial aviation today 

In a previous post on unusual attitude I talked about the use of pitch ladders as a means of providing greater attensity to aircraft attitude as well as a better indication of what the aircraft is dong, having entered into it. There are of course still disadvantages with this because such data in a commercial aircraft is usually presented ‘eyes down’, and in high stress, high workload situations it can be difficult to maintain an instrument scan pattern. There is however an alternative, and one that has a number of allied advantages. Continue Reading…

R101 crash (Image source: public domain)

The R-101 is as safe as a house, except for the millionth chance. (Comment made shortly before boarding the doomed airship headed to India on its first real proving flight, 4 October 1930. The day before he had made his will.)

Lord Thomson, Secretary of State for Air

Unreliable airspeed events pose a significant challenge (and safety risk) because such situations throw onto aircrew the most difficult (and error prone) of human cognitive tasks, that of ‘understanding’ a novel situation. This results in a double whammy for unreliable airspeed incidents. That is the likelihood of an error in ‘understanding’ is far greater than any other error type, and having made that sort of error it’s highly likely that it’s going to be a fatal one. Continue Reading…

risky shift