Three LOPs vs two LOPs: which is true?

• A. Three lines of position should be preferred over two.
• B. Two lines are sufficient and faster.
• C. One line is the best for accuracy.
• D. LOPs estimate position with no error.

Answer: (A)

The main idea here is that lines of position (LOPs) are used to pinpoint your location by where their lines cross on a chart. Each LOP adds information, and more independent LOPs let you check and refine the position.

With two LOPs, you can locate a point where the two lines intersect, but each measurement carries error. The true position may lie somewhere near that intersection, and you don’t have a built-in way to tell how far off you might be. Adding a third independent LOP gives a redundancy that lets you check consistency among the lines and, in practice, compute a best-fit position that minimizes the effect of individual measurement errors. This makes the final fix more reliable and typically more accurate.

One line cannot determine a unique position at all, since an entire line represents many possible locations along it. So you need at least two lines to define a likely area, and three lines to tighten that into a more precise fix with error checks. The statement that three lines should be preferred over two reflects the benefit of redundancy and improved accuracy when multiple independent measurements are available.