ARPA Written Exam Solution Manual Fully Solved
Steady state tracking - Answers Both us and contact as maintaining course and speed for at least 1 min.
ARPA predictions - Answers Based on averages of 3 minutes of historical input data.
Good ARPA inputs - Answers Requires steady state tracking [no course/speed change by either vessel in
3 minute history].
Tracking gate - Answers As track confidence increases, gate size decreases.
Restricted waters/harbor - Answers Smaller gate size.
Open ocean - Answers Larger gate size.
Acquire (ARPA) - Answers Direct ARPA begin tracking of selected target [track and vector].
Drop (ARPA) - Answers Direct ARPA cease tracking and projection of selected target [stop track and
vector].
Hook (ARPA) - Answers Direct ARPA display detailed target info on selected targets.
Unhook (ARPA) - Answers ARPA ceases display of detailed info.
Tracking - Answers Based on either 1-3 min of steady state tracking, can track 20 simultaneously,
continue 5/10 sweeps, past position.
Warnings (ARPA) - Answers Signal for guard rings/areas; signal for CPA range/time signal lost for target.
Accuracy (ARPA) - Answers Standards for some targets (within 0.7 nm) = less stringent than manual
plotting.
Trial maneuver - Answers Capable stimulating effect on all tracked targets of maneuver by ownship.
AIS - Answers Unaffected by sea/rain, shows us stuff radar and eyes can't see like around bends, better
at diffracting around islands, still have vessel info in restricted visibility.
RADAR - Answers Detect target w/o AIS, based on ship's heading and collision avoidance.
Glint - Answers As the ship goes over the waves the radar hits at different parts of the ship.
Target Swap - Answers More than one target in a gate at the same time, causes target to switch/swap
targets.
Centroid Shift - Answers Changes in the target aspect → vector loss/shift.
SP73 Errors - Answers 1116 → 1000 yd CPA, 1116 → 1 min CPA, 1116 → 1 kt true speed, 1116 → 6
degrees true course.
Steady state tracking - Answers Both us and contact as maintaining course and speed for at least 1 min.
ARPA predictions - Answers Based on averages of 3 minutes of historical input data.
Good ARPA inputs - Answers Requires steady state tracking [no course/speed change by either vessel in
3 minute history].
Tracking gate - Answers As track confidence increases, gate size decreases.
Restricted waters/harbor - Answers Smaller gate size.
Open ocean - Answers Larger gate size.
Acquire (ARPA) - Answers Direct ARPA begin tracking of selected target [track and vector].
Drop (ARPA) - Answers Direct ARPA cease tracking and projection of selected target [stop track and
vector].
Hook (ARPA) - Answers Direct ARPA display detailed target info on selected targets.
Unhook (ARPA) - Answers ARPA ceases display of detailed info.
Tracking - Answers Based on either 1-3 min of steady state tracking, can track 20 simultaneously,
continue 5/10 sweeps, past position.
Warnings (ARPA) - Answers Signal for guard rings/areas; signal for CPA range/time signal lost for target.
Accuracy (ARPA) - Answers Standards for some targets (within 0.7 nm) = less stringent than manual
plotting.
Trial maneuver - Answers Capable stimulating effect on all tracked targets of maneuver by ownship.
AIS - Answers Unaffected by sea/rain, shows us stuff radar and eyes can't see like around bends, better
at diffracting around islands, still have vessel info in restricted visibility.
RADAR - Answers Detect target w/o AIS, based on ship's heading and collision avoidance.
Glint - Answers As the ship goes over the waves the radar hits at different parts of the ship.
Target Swap - Answers More than one target in a gate at the same time, causes target to switch/swap
targets.
Centroid Shift - Answers Changes in the target aspect → vector loss/shift.
SP73 Errors - Answers 1116 → 1000 yd CPA, 1116 → 1 min CPA, 1116 → 1 kt true speed, 1116 → 6
degrees true course.
