Until about a year ago I was a GPS virgin except for the Garmin non moving map thingy in rented airplanes that I never really understood.
Then I invested in a Skymap (not the colour one). So with my new toy I went out in the car and found to my disgust that it was up to 300 metres out of place with regards to roads, but which road is in a dead straight line as shown on the display?
It is all about the ammount of effort put into the data card which plugs into the back.
I will not trust it as an approach aid for this reason, I have sat in my car at the threshold of RAF Waddington and the thing has put me about 250m out of place. I know that it is not just my unit because I spoke to a very helpful guy at Skymap who sent me the latest memory card which did not improve the situation.
I think that the Garmin GPS's have a better database from what I have seen, but 250 metres en route isn't bad really.
Another word of warning... with regards to the instantaneous moving map information they present you with, I feel that I am beginning to lose "spatial awareness" from the VOR and ADF which took a long time to aquire.
Oh yes there is a dead spot on the north Norfolk coast.
B