Archives For Psychology

Human psychology and the role it plays in decision making under uncertainty.

Joshua Brown screen grab

Keep your eyes on the road, and your hands upon the wheel…

The first fatality involving the use of Tesla’s autopilot* occurred last May. The Guardian reported that the autopilot sensors on the Model S failed to distinguish a white tractor-trailer crossing the highway against a bright sky and promptly tried to drive under the trailer, with decapitating results. What’s emerged is that the driver had a history of driving at speed and also of using the automation beyond the maker’s intent, e.g. operating the vehicle hands off rather than hands on, as the screen grab above indicates. Indeed recent reports indicate that immediately prior to the accident he was travelling fast (maybe too fast) whilst watching a Harry Potter DVD. There also appears to be a community of like minded spirits out there who are intent on seeing how far they can push the automation… sigh.  Continue Reading…

A requirements checklist that can be used to evaluate the adequacy of HMI designs in safety critical applications. Based on the work of Nancy Leveson and Matthew Jaffe.

qantas-vh-vzr-737-838-640x353

Deconstructing a tail strike incident

On August 1 last year, a Qantas 737-838 (VH-VZR) suffered a tail-strike while taking off from Sydney airport, and this week the ATSB released it’s report on the incident. The ATSB narrative is essentially that when working out the plane’s Takeoff Weight (TOW) on a notepad, the captain forgot to carry the ‘1’ which resulted in an erroneous weight of 66,400kg rather than 76,400kg. Subsequently the co-pilot made a transposition error when carrying out the same calculation on the Qantas iPad resident on-board performance tool (OPT), in this case transposing 6 for 7 in the fuel weight resulting in entering 66,400kg into the OPT. A cross check of the OPT calculated Vref40 speed value against that calculated by the FMC (which uses the aircraft Zero Fuel Weight (ZFW) input rather than TOW to calculate Vref40) would have picked the error up, but the crew mis-interpreted the check and so it was not performed correctly. Continue Reading…

To err is human, but to really screw it up takes a team of humans and computers…

How did a state of the art cruiser operated by one of the worlds superpowers end up shooting down an innocent passenger aircraft? To answer that question (at least in part) here’s a case study that’s part of the system safety course I teach that looks at some of the casual factors in the incident.

In the immediate aftermath of this disaster there was a lot of reflection, and work done, on how humans and complex systems interact. However one question that has so far gone unasked is simply this. What if the crew of the USS Vincennes had just used the combat system as it was intended? What would have happened if they’d implemented a doctrinal ruleset that reflected the rules of engagement that they were operating under and simply let the system do its job? After all it was not the software that confused altitude with range on the display, or misused the IFF system, or was confused by track IDs being recycled… no, that was the crew.

Matrix (Image source: The Matrix film)

The law of unintended consequences

There are some significant consequences to the principal of reasonable practicability enshrined within the Australian WHS Act. The act is particularly problematic for risk based software assurance standards, where risk is used to determine the degree of effort that should be applied. In part one of this three part post I’ll be discussing the implications of the act for the process industries functional safety standard IEC 61508, in the second part I’ll look at aerospace and their software assurance standard DO-178C then finally I’ll try and piece together a software assurance strategy that is compliant with the Act. Continue Reading…

What burns in Vegas…

Ladies and gentlemen you need to leave, like leave your luggage!

This has been another moment of aircraft evacuation Zen.

If you’re interested in observation selection effects Nick Bostrum’s classic on the subject is (I now find out) available online here. A classic example of this is Wald’s work on aircraft survivability in WWII, a naive observer would seek to protect those parts of the returning aircraft that were most damaged, however Wald’s insight was that these were in fact the least critical areas of the aircraft and that the area’s not damaged should actually be the one’s that were reinforced.