On Saturday I mentioned Alan Cooper's anecdote about a design flaw in a military GPS device. An email correspondent, Jim Hanna, who I'm quoting with permission, clarifies the story:
I have followed this story closely, from an interest in GPS and an interest in failure modes of technical infrastructure. I read an account shortly after the incident that included much more detail than you usually see in reporting on these things. It was from the web version of some newspaper, but I haven't been able to find the link. Anyway, this account differs in a small but significant way from the one you cite. It said that the guy with the GPS had the target coordinates in the device and was about to perform some transformation on them before transmitting them (via a separate communication channel, which I believe was voice radio communication. He lost battery power, and inserted new batteries. When the GPS powered up, it displayed it's own position first. That's what all GPS units I've seen normally do. The problem was that the guy had a very short time to get the coordinates to the aircraft which was enroute and nearing the target zone. So in his haste, he forgot that the coordinate displayed was not the coordinate he was working on when the device powered off, so he did the transformation on the coordinates he saw (his present position) and radioed them to the aircraft.
This is consistent with my experience from using similar devices and suggests the problem is as much one of training as one of design.
Jim cites this URL, which quotes Stephen Cole writing for The Strategy Page, as his probable source.
Cooper would doubtless argue that design and training are inverse sides of the same coin. For example, Cole's account shows that the "design" of the entire system was such that a transform from Navy to Air Force coordinates was evidently needed:
A few minutes before the deadly mistake, he used his PLGPS to determine the target's location in degrees, minutes, and seconds so it could be attacked by Navy F-18s. Then, he recalculated the position in "decimal fractions of a degree" which is the way that the Air Force wants it.
These tales of non-interoperability used to be funnier than they seem now.
Former URL: http://weblog.infoworld.com/udell/2002/06/17.html#a303