Thanks to all of you who contributed to the debate most of which was concluded on the CWU Postmasters Facebook page. Some great premises of how the conundrum could be explained. As I mentioned, there may well be several different explanations but here is mine – particularly worded to provide a background to perhaps a further debate on whether the original conviction should be overturned or not?
Let’s start with the last event where the error was discovered. It was a particularly hot day, but any of you who have lived and worked in a hot environment will know that when the ambient air temperature is 40C plus you don’t actually notice much of a difference whether the temp is 41C or 49C because you are in shade most of the time and at those temperatures the air is most often still and dry.
The checkpoint where the truck was stopped was only a few hundred yards outside the factory. The scales used in this temporary weighbridge were calibrated that day and in that heat. They were also of a different manufacturer from the weighbridge in the factory. When the truck was stopped and found to weigh 45T the driver told them he had just had it weighed and it showed 35T. SO the police took the truck back to the factory and sure enough the weighbridge registered 35T. It was clearly in error. An investigation took place. All digital weighing devices have to allow for the ambient heat in their calculations and the heat sensor was tested and working fine. The software however revealed the problem. The programmer for the manufacturer was from Scotland. He had no idea that ambient temperatures could go over 40C but nevertheless he allowed for a maximum of 45C in his algorithm (canny bugger!) Unfortunately the ambient air temperature that day was 49C and the algorithm was such that it resulted in the weight being calculated far lower than it actually was.
Realising the previous instance of this error had caused a fatality the Police looked at the temperature records at the time of that incident. They found that that day the ambient air temperature at the Factory was 49C but the day after when the truck was brought back to weigh the temperature was only 42C. Thus the weight was recorded too low on the day of the accident but completely different weight the very next day.
Who was at fault here. Australia is the land of the man who sued God after all. Was it the programmer? Was it the weighbridge operator for not calibrating the weighbridge every day even though the manual said it was only needed to be done once a month? Was there a contract involved? Did the weighbridge manufacturer provide warranty? What would happen if the warranty had expired? Was the driver still liable because he should have tested the efficacy of the weighbridge everytime he used it?
Lots of questions and this time I have no real answers but would be happy to join in a discussion on it.