As usual for me, a
BBC News article.
According to the article, the continent of Australia (and presumably Tasmania too) is moving northwards at about 7cm per year, and this is causing problems with GPS systems. The GPS device reports the true position (latitude and longitude) - but the map data that it uses to work out where it is and what's around it uses latitudes and longitudes that were calculated in 1994 and have been fixed since then. Consequently the device thinks it's about 1.5 metres north of where it actually is. This is not a problem in most cases, but if the GPS is used in controlling automatic vehicles (e.g. farm tractors mentioned in the article) then there's potential for significant problems.
As a short-term fix, the Australian national mapping system will be shifted north by 1.8 metres on 1 January 2017 - this is a bit further than it needs to be, but will give a few years while the map and the actual co-ordinates are getting closer together. The long-term intention is to introduce a more flexible mapping system that can keep up with the movement continuously.
