A few weeks ago we were in US to fly in a hot air balloon competition. The digital map we received, without calibration file, was made with NAD27 CONUS map datum.

The map datum was in the list of the program, so that would not be a problem we tought. But after calibrating the map, the grid displayed on the screen was about 200 m to the north of the grids drawn on the map.

When we started the moving map, the arrow was on the right spot, but the coordinates were wrong.

When i asked the organisation if there was a problem with the map, they answered me that they did not have a problem with the Oziexplorer program. So i guess they meant that Compe could not handle this map datum. According to what they explaned, 200 m is the differnce between NAD27 and WGS84.

If you want i can transfer the map and the map datum file to you via dropload.