The 'reliability diagram' in the margin of every topographical map is one indication of the accuracy with which the features have been depicted and along with the 'surveyed in ....' date, gave us a reasonable level of confidence in using the cartographic offering - till about a decade ago. Today, as Ed Parsons says "...it takes a long time to get updated maps to users"...and the long time is about 'two years'.

The updating of digital navigation maps has been in discussion lists and blogs for some time now. The debate on reliability of crowd-sourced data is an offspring of such ruminations which have so far been inconclusive but crowd-sourced data is here to stay. I find the Google Earth Community posting way more reliable and updated than the temporal resolution of Google's map updates though I do remember a story of a motorist driving into a lake since the PND did not depict a lake which had come and submerged the road due to a dam close by. The scene in India is more reliable due to the age old technique of asking a passerby for directions, whether riding a bullock-cart or a car with a PND, we just ASK... better than driving into a lake. So, all that most of us who do use PNDs need, is a bit of patience and acceptance of genuine data updating problems. What we also need is a highlighted reminder on the screen of our PND stating the '...best before ...'.