USCG Exam PracticeDead reckoning — DR plot maintenance
A navigator obtains a bearing on a lighthouse at 0930 but cannot obtain a second simultaneous LOP. The 0930 LOP is advanced along the DR track to 1000, when a second bearing is taken. The resulting position is BEST described as a:
- A. Fix, because two LOPs were used
- B. Dead reckoning position, because no external reference was used at 1000
- ✓ Running fix, less accurate than a fix from simultaneous LOPsCorrect
- D. Estimated position, because the first LOP was taken from a single object
Why C is correct
Bowditch Ch. 7 §702 defines a running fix as one obtained when LOPs cannot be taken simultaneously; the first LOP is advanced along the DR track to the time of the second observation. The source explicitly states a running fix is less accurate than a fix from simultaneous LOPs.
Cited:Bowditch Ch. 7 §702