Deck Navigation (Supplementary) USCG Question #778 (Set 2)

When using GPS, how many theoretical position lines are required for a two- dimensional fix?

Official USCG Answer & Rule Citation

Correct Answer: Option C — 3

GPS determines position through trilateration. While two satellites provide a 2D fix in theory, a third satellite is required to solve for the receiver's clock bias, which is essential for accurate timing and distance calculations. Therefore, three lines of position are the minimum for a valid 2D fix.

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