The directional error curve as booth elliptical lemniscate

There are two aspects of position coordinates accuracy in navigation: global accuracy and local accuracy – relative to navigational dangers. The latter case refers to the assessment of position (distance) accuracy in respect to the nearest navigational danger, a hazard to navigation. The directional error is a relevant measure for such assessment. The directional error curve is analyzed in this article as a particular case of the Booth elliptical lemniscate. The curve graph illustrates the confidence interval of point position errors in a given direction (about 68%).