Dead Reckoning (DR) is a navigation method that estimates a person’s current track, groundspeed, and position based on previously known locations. While DR isn’t widely used in modern navigation, pilots can still apply its principles. For instance, they might use it to predict their estimated time of arrival (ETA) at a future point or to adjust their heading to get back on course. Some electromechanical navigation devices also utilize DR techniques. In cases where the input to certain Flight Management Systems fails, dead reckoning becomes the default mode. This situation means that the system relies on heading and true airspeed, possibly adjusted for past wind effects, instead of using data from Global Positioning Systems (GPS) or other navigation tools. Pilots may not notice this shift right away, but it can significantly reduce navigational accuracy.
