If the lines of position must be advanced or retired by an hour or more, convention dictates that the result is referred to as a " running fix ".
22.
In either case, the lines of position, if taken at different times, must be advanced or retired to correct for the movement of the ship during the interval between observations.
23.
Sight is defined as the observation of the altitude, and sometimes also the azimuth, of a celestial body for a line of position; or the data obtained by such observation.
24.
A straight line called the " azimuth line of position " is drawn on a map, and on most common map projections this is a close enough approximation to the isoazimuth.
25.
The TDOA and FDOA results provide a finite number of locations on the Earth s surface, and therefore, lines of position ( LOPs ) are determined from the TDOA and FDOA results.
26.
Each LOP is then constructed from its associated AP by striking off the azimuth to the body, measuring intercept toward or away from the azimuth, and constructing the perpendicular line of position.
27.
The resulting line of position ( " LOP " ) is a small segment of the circle of equal altitude, and is represented by a straight line perpendicular to the azimuth of the celestial body.
28.
Though virtually on the line of position that Earhart reported flying before she vanished, Samoa was hundreds of miles from Howland Island, a speck of land north of the equator where Earhart had planned to refuel.
29.
Although in theory two lines of position ( LOP ) are enough to define a point, in practice'crossing'more LOPs provides greater accuracy and confidence, especially if the lines cross at a good angle to each other.
30.
The second line of defense was not visible from the first line of positions, and allowed the fighters to fall back, either to escape a heavy bombardment, to continue retreating or to furnish a rallying point for counterattack.
