High Quality Content by WIKIPEDIA articles! In navigation, dead reckoning (also ded (for deduced) reckoning or DR) is the process of calculating one`s current position by using a previously determined position, or fix, and advancing that position based upon known or estimated speeds over elapsed time, and course. While traditional methods of dead reckoning are no longer considered primary means of navigation, modern inertial navigation systems, which also depend upon dead reckoning, are very widely used.