[SystemSafety] 2012 Super Puma Ditchings

[Peter Bernard Ladkin]

Something I forgot to say.

I posted a similar note to a closed mailing list about aviation, and received a note from a
colleague who used to fly intercontinentally for a major NA airline and who was instrumental in
setting up its Flight-Operations Quality Control System.

He noted an incident which happened to him in which he made a judgement that things weren't quite as
they were being displayed, and was right (and thereby handled the flight more safely). Ultimately
because of what I would call an ambiguous connector - someone had plugged in a plug the wrong way
round.

There are plugs you can plug in to sockets for which it doesn't matter which pins connect to which
receptors. Such as electric circuits in buildings in NA or Germany. There are plugs you can plug in
to sockets, for which it does matter which way they connect. It can easily be guaranteed that the
pins are connected to the female connectors as they should be, usually accomplished by externally
visible plug geometry, for example trapezoidal housing, as with RS232, mini-USB or micro-USB,
sometimes by externally-invisible plug geometry, such as USB (where try, and then invert if the
first attempt doesn't work). Or the new European-standard 7-pin connector for charging electric road
vehicles.

Then there are plug-connector combinations which are ambiguous, such as the Super Puma case, and the
case leading to the incident in which my colleague was involved. Somebody installed a plug the
"wrong way round".

This isn't any case to be referred to a flight provider's SMS. This is a design flaw. There are
simple ways known to ensure that connections which require a specific configuration can only be made
in that configuration, such as RS232, RJ45, USB, mini-USB, micro-USB and so on. Then apparently
there are critical contact connection designs of the same nature which allow that a plug-type
connection can be incorrect. Why? Does one have to quote Norman on affordances once again, or can
one just say out loud that this is an inexcusable design flaw?

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de