iPhone compass apps will be inaccurate regardless of whether or not the apps/compass has been recalibrated or not. This will known circumstance is due to residual (after calibration) compass azimuth deviation error. The calibration procedure accounts for placement of magnetic/electromagnetic influences within the iPhone itself and (to a limited extent) magnetic/electromagnetic influences within the immediate surroundings of the iPhone. Certainly, all environmental influences are NOT accounted for; and the iPhone compass app error varies throughout the entire 360 degree range of measurement.Take a look at a new set of blog posts that deals with this compass error issue. Go to “tru-path.org” for multiple tests and examples of what can be done to correct iPhone compass error.