CMRT Navigation & Chart Integration 2 — Questions and Answers
Question 1: What does 'Closest Point of Approach' (CPA) indicate in ARPA/MARPA displays?
- The distance at which own ship will pass closest to a tracked target if both vessels maintain current course and speed (Correct answer)
- The maximum range of the radar
- The point where two radar beams intersect
- The minimum range ring setting
Correct answer: The distance at which own ship will pass closest to a tracked target if both vessels maintain current course and speed
CPA is the minimum predicted distance between own ship and a tracked target based on current vectors, used to assess collision risk.
Question 2: What is TCPA in radar target tracking?
- Total Compass Position Angle
- Time to Closest Point of Approach — the time until a tracked target reaches its CPA (Correct answer)
- Transmitter Control Pulse Amplitude
- Terrain Clutter Prevention Algorithm
Correct answer: Time to Closest Point of Approach — the time until a tracked target reaches its CPA
TCPA (Time to Closest Point of Approach) indicates how many minutes until a tracked target reaches its closest point to own ship.
Question 3: What is the function of a guard zone (alarm zone) in a radar navigation system?
- To restrict radar transmission power near shore
- To trigger an alarm when a radar target enters a predefined area around own ship (Correct answer)
- To prevent false echoes from sea clutter
- To mark areas of prohibited fishing
Correct answer: To trigger an alarm when a radar target enters a predefined area around own ship
A guard zone triggers an audible or visual alarm when any radar target enters the defined area, alerting watchkeepers to potential close-quarters situations.
Question 4: Which IEC standard governs the performance requirements for shipborne radar equipment?
- IEC 60945
- IEC 62388 (Correct answer)
- IEC 61162
- IEC 60529
Correct answer: IEC 62388
IEC 62388 specifies the minimum performance requirements, methods of testing, and required test results for shipborne radar equipment.
Question 5: What is the purpose of a heading line (HL) on a radar display?
- To indicate the direction of the radar beam at maximum power
- To show the vessel's current heading directly from the bow on the radar display (Correct answer)
- To mark the boundary of the radar's blind sector
- To indicate true north on the display
Correct answer: To show the vessel's current heading directly from the bow on the radar display
The heading line extends from own ship's position in the direction of the vessel's bow, providing a continuous reference to own ship's heading on the radar display.
Question 6: When integrating AIS with radar, what is the term for a target shown as both an AIS contact and a radar echo?
- Ghost target
- Sleeping target
- Fusion target or CONSORT target (Correct answer)
- Primary radar target
Correct answer: Fusion target or CONSORT target
A fusion target (sometimes called a CONSORT target) is one where the AIS transponder signal and the radar echo have been correlated and merged into a single displayed target.
CMRT Navigation & Chart Integration 2
What does 'Closest Point of Approach' (CPA) indicate in ARPA/MARPA displays?