Radar ARPA Theory Comprehensive Review 2026 |
Questions & Correct Answers | Graded A+
1. Describe the purpose of the tracking gate in ARPA systems and its impact on
target management.
The tracking gate reduces the number of targets in a given bearing
range for the sweeps of the antenna.
The tracking gate is irrelevant to target management.
The tracking gate is used to initiate contact plotting.
The tracking gate increases the range of targets displayed on the
screen.
2. If an ARPA system is continuously alarming due to a target violating
CPA/TCPA limits, what actions should a navigator take to ensure safety?
Turn off the ARPA system to stop the alarm.
Ignore the alarm if the target is not visible.
Adjust the vessel's course or speed to maintain safe distances from
the target.
Increase the target's speed to avoid collision.
3. If a vessel relies solely on ARPA for navigation without maintaining a proper
lookout, what potential risks could arise?
Improved navigation accuracy.
Reduced operational costs.
Enhanced communication with other vessels.
Increased risk of collision due to lack of situational awareness.
,4. ARPA must have a visual and/or audible signal for which of the following?
Breach of bow crossing range only.
Breach of range or transit zone only.
Breach of range or transit zone, CPA and TCPA, and Lost Target.
5. What type of error is most frequently associated with ARPA systems that
does not relate to how data is displayed?
A failure in the radar signal reception
An input error from your Doppler speed log
A malfunction in the ARPA processor
An incorrect setting of the ARPA parameters
6. If a vessel is navigating in a coastal area and experiences significant wave
action, which stabilization method should be prioritized to ensure accurate
ARPA readings?
None of the above
Heads-up Unstabilized
Ground stabilization
Sea Stabilization
7. Describe the implications of violating CPA/TCPA thresholds in ARPA systems.
Violating CPA/TCPA thresholds can trigger alarms and indicate
potential navigational risks, but does not necessarily mean
immediate danger.
There are no implications for violating CPA/TCPA thresholds.
CPA/TCPA violations are only relevant for large vessels.
, Violating CPA/TCPA thresholds guarantees a collision will occur.
8. Your ARPA has automatic speed inputs from the log. Due to currents, the log
is indicating a faster speed than the speed over the ground. What should you
expect under these circumstances?
The range of initial target acquisition will be less than normal.
The generated TCPA will be later than the actual TCPA.
The generated CPA will be less than the actual CPA.
The target's true course vector will be in error.
9. What factors influence the accuracy of true vectors in ARPA systems?
Radar frequency
Weather conditions
Course and speed input
Operator experience
10. What does ARPA stand for in the context of navigation systems?
Automatic Radar Performance Analyzer
Automated Radar Processing Application
Automatic Radar Plotting Aid
Advanced Radar Positioning Assistant
11. Describe the significance of the Minimum Keyboard and Display (MKD) in
ARPA systems.
The MKD is a type of radar used in ARPA systems.
The MKD refers to the minimum distance required for radar plotting.
, The MKD is an obsolete term in modern navigation systems.
The MKD is crucial for user interaction with ARPA systems, allowing
operators to input data and receive visual information.
12. Which of the following is the most probable source of error affecting the
accuracy of a running fix?
Error in observing the bearing used
Error in the assumed speed used to advance the LOP
Error in identifying the ATON used
Error in plotting the bearings used
13. If an ARPA system indicates a CPA of 0.5 nautical miles and a TCPA of 10
minutes for a designated target, what action should a navigator consider
taking?
Increase speed to reach the target faster.
Maintain current course and speed.
Ignore the data as it is not relevant.
Adjust course to avoid a potential collision.
14. What is the primary function of the tracking gate during Centroid Shift in
ARPA systems?
The target has returned to a reciprocal course and the Radar cannot
track it
The tracking gate locates itself over the part of the target with the
weakest response
The tracking gate locates itself over the part of the target with the
greatest response
Questions & Correct Answers | Graded A+
1. Describe the purpose of the tracking gate in ARPA systems and its impact on
target management.
The tracking gate reduces the number of targets in a given bearing
range for the sweeps of the antenna.
The tracking gate is irrelevant to target management.
The tracking gate is used to initiate contact plotting.
The tracking gate increases the range of targets displayed on the
screen.
2. If an ARPA system is continuously alarming due to a target violating
CPA/TCPA limits, what actions should a navigator take to ensure safety?
Turn off the ARPA system to stop the alarm.
Ignore the alarm if the target is not visible.
Adjust the vessel's course or speed to maintain safe distances from
the target.
Increase the target's speed to avoid collision.
3. If a vessel relies solely on ARPA for navigation without maintaining a proper
lookout, what potential risks could arise?
Improved navigation accuracy.
Reduced operational costs.
Enhanced communication with other vessels.
Increased risk of collision due to lack of situational awareness.
,4. ARPA must have a visual and/or audible signal for which of the following?
Breach of bow crossing range only.
Breach of range or transit zone only.
Breach of range or transit zone, CPA and TCPA, and Lost Target.
5. What type of error is most frequently associated with ARPA systems that
does not relate to how data is displayed?
A failure in the radar signal reception
An input error from your Doppler speed log
A malfunction in the ARPA processor
An incorrect setting of the ARPA parameters
6. If a vessel is navigating in a coastal area and experiences significant wave
action, which stabilization method should be prioritized to ensure accurate
ARPA readings?
None of the above
Heads-up Unstabilized
Ground stabilization
Sea Stabilization
7. Describe the implications of violating CPA/TCPA thresholds in ARPA systems.
Violating CPA/TCPA thresholds can trigger alarms and indicate
potential navigational risks, but does not necessarily mean
immediate danger.
There are no implications for violating CPA/TCPA thresholds.
CPA/TCPA violations are only relevant for large vessels.
, Violating CPA/TCPA thresholds guarantees a collision will occur.
8. Your ARPA has automatic speed inputs from the log. Due to currents, the log
is indicating a faster speed than the speed over the ground. What should you
expect under these circumstances?
The range of initial target acquisition will be less than normal.
The generated TCPA will be later than the actual TCPA.
The generated CPA will be less than the actual CPA.
The target's true course vector will be in error.
9. What factors influence the accuracy of true vectors in ARPA systems?
Radar frequency
Weather conditions
Course and speed input
Operator experience
10. What does ARPA stand for in the context of navigation systems?
Automatic Radar Performance Analyzer
Automated Radar Processing Application
Automatic Radar Plotting Aid
Advanced Radar Positioning Assistant
11. Describe the significance of the Minimum Keyboard and Display (MKD) in
ARPA systems.
The MKD is a type of radar used in ARPA systems.
The MKD refers to the minimum distance required for radar plotting.
, The MKD is an obsolete term in modern navigation systems.
The MKD is crucial for user interaction with ARPA systems, allowing
operators to input data and receive visual information.
12. Which of the following is the most probable source of error affecting the
accuracy of a running fix?
Error in observing the bearing used
Error in the assumed speed used to advance the LOP
Error in identifying the ATON used
Error in plotting the bearings used
13. If an ARPA system indicates a CPA of 0.5 nautical miles and a TCPA of 10
minutes for a designated target, what action should a navigator consider
taking?
Increase speed to reach the target faster.
Maintain current course and speed.
Ignore the data as it is not relevant.
Adjust course to avoid a potential collision.
14. What is the primary function of the tracking gate during Centroid Shift in
ARPA systems?
The target has returned to a reciprocal course and the Radar cannot
track it
The tracking gate locates itself over the part of the target with the
weakest response
The tracking gate locates itself over the part of the target with the
greatest response
