Navigation General · ARPA
A major limitation of ARPA that the watchkeeper must understand is:
- AARPA cannot display targets at ranges greater than 12 miles
- BARPA cannot detect targets that are stationary
- CARPA tracking accuracy depends on the quality of the radar echo; small or poor-reflecting targets may be tracked inaccurately or lost✓ Correct
- DARPA requires manual input of own ship's speed and course to compute target vectors
Explanation
ARPA tracking relies on the consistency and quality of the radar echo. Targets with poor radar cross-section, those in heavy clutter, or those undergoing evasive maneuvers may be tracked inaccurately or dropped. The watchkeeper must never rely solely on ARPA alarms and must verify CPA data against manual observation. Modern ARPA uses own ship sensors (GPS/gyro/log) for motion input, not manual entry.
Authority: Radar Navigation Manual (Pub. 1310), Ch. 6
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Related Navigation General questions
- ARPA
According to ARPA capabilities, which of the following does ARPA automatically provide?
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On an ARPA display set to TRUE MOTION mode, own ship's echo:
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After own ship executes a course change to avoid a collision, the ARPA trial maneuver function is useful because it:
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ARPA 'target swap' occurs when:
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The ARPA 'trial maneuver' function allows the navigator to:
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A known limitation of ARPA target tracking is 'target swap', which can occur when: