Principles of Celestial Navigation

A Day in the Life of a Navigator » Obtaining a Running Fix

Chief Quartermaster Tim Sheedy, U.S. Navy, demonstrates how various celestial sights are reduced and plotted during a day in the life of a navigator

Chief Sheedy: Now that we’ve completed the morning Sun line, local apparent noon, and afternoon Sun line, we can now obtain a running fix. I’m going to show you how to do that. The afternoon Sun line is plotted on the Universal Plotting Sheet, properly labeled 19:35 and 58 seconds, Sun. We need to take the 11:45:15 Sun line from our estimated position at time 15:45 and advance it based on our ordered course and speed, course 318 6 knots. As stated previously, I like to draw hash marks showing that I advanced the line of position. Properly label 11:45:15, Sun. Now we’ll take the latitude, 15:45 LAN, which is also a line of position, and move it based on our ordered course and speed and advance that line of position. Properly label 15:45 LAN and hash marks showing that we advanced that LOP. Because we’re using advanced lines of position, this constitutes a running fix, where the three intersect. We’ll label it with a circle because it’s a celestial fix, and DR out. The running fix is at 32 degrees 21 decimal 3 North, 055 degrees 16 minutes West.

screenshot showing Universal Plotting Sheet with 1935 Sun line, and running fix based on advanced lines of position