Assumed Position (AP) / Chosen Position

Definition

For tabular sight reduction the latitude is rounded to a whole degree and the longitude chosen so LHA becomes whole, placing the AP within about 30 nautical miles of the estimated position. Calculator or app methods can use the dead reckoning position directly with no rounding. The resulting position line is independent of the AP chosen; only the length and direction of the intercept change, which is a useful arithmetic check.