Radar Observer · Navigation — Parallel Indexing
Parallel indexing is a radar technique that lets the navigator:
- AMonitor cross-track distance off a planned track by watching a fixed radar object trail along a pre-set parallel line✓ Correct
- BMeasure the height of a lighthouse
- CAcquire ARPA targets automatically
- DTune the receiver
Explanation
In parallel indexing the navigator draws a line on the display parallel to the intended track at the planned passing distance from a fixed charted object; keeping that object's echo running along the line confirms the ship is on track, giving a continuous, real-time check of cross-track error in pilotage waters.
Authority: Bowditch (Pub. No. 9); IMO guidance on parallel indexing
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