One of the common questions that gets asked how often should I calibrate my compass???? Well If your always flying in the same spot there really should be no need to re-calibrate OR is there? I say yes. The reason I say yes is every once in awhile I will upload to Exmaps.com. On their site they have this nice little option that warns you of errors in your telemetry file. The last three entries I put into Exmaps came up with a compass calibration error. So the other day I re-calibrated and flew around my normal spots. Uploaded the telemetry file to Exmaps and the error is now gone. So this is a good way to check to see if something is not right. The errors were very short but they were there and could lead to more serious problems.