NavList:

Frank,

        Well done! Thanks for figuring this out. Although I harboured the image of the underpaid programmer pounding the keys and naively lifting the rhumbline distance formula from some navigational text, I could not have imagined that something as wrong-headed as the square-root-of-sum-of-squares was being used.

I don’t think that this should be just shrugged off. There are grounds here for a Navlist crusade. The inflight software is presumably developed by some third party company and sold to the airlines for serious money. They should be getting something better than this and we, the travelling public, should not have to suffer the affront of having to gaze upon incorrect navigational data! I have seen the system in question in use on other airlines so it is probably quite wide spread and maybe universal in Airbus planes. Does anyone on Navlist have inside information on its source? Of course maybe the problem will just fix itself when a new generation of software comes along.

BTW although the source of the error has been discovered, the puzzles I posed still stand for anyone interested in trying them,

Regards,

Robin Stuart