Course Deviation : The length of a line made by projecting a course length onto a horizontal plane. In practice, the horizontal displacement between two stations regardless of directions. (Bul D20)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}