ARPA Written Exam - OOD
What controls can be adjusted if known targets are not being detected on radar? - Answer-Gain,
suppressions, range scale
What factors contribute to the assessment of risk of collision? - Answer--Relative motion line
(CPA/TCPA)
-Aspect
-Error in calculations
When will a radar contact remain stationary on a relative motion radar display? - Answer-When it is on
the same course and speed as your vessel
If a radar contact is dead ahead and the range decreases without a change in bearing, what is the
estimated speed of the contact? - Answer-Dead in the Water (DIW)
If a radar contact is directly astern and the range decreases without a change in bearing, what is the
estimated speed of the contact? - Answer-15 knots
How can the closest point of approach (CPA) of a contact on a relative motion radar be determined? -
Answer-After marking the contact at least twice over a minute
What is a radar display called when North is always at the top of the screen? - Answer-Stabilized display
What inputs are needed to maintain a North-Up, True Motion display on radar? - Answer-Gyro course,
speed log
, Besides ARPA information, what should an ARPA user consider? - Answer--Limitations of the information
-Rules of the road
-Circumstances and external considerations
In restricted visibility, what should you avoid when altering course for a vessel forward of your beam? -
Answer-Avoid altering course to port except in overtaking situations
When two ARPA Equipped Ships Collide, What Is Typically True? - Answer-Both vessels are likely to be
found at fault
When Using an ARPA, What Should You Consider to Evaluate Displayed Information? - Answer-
Navigational constraints may require a target vessel to change course
What Information Is Least Dependent on ARPA Processing? - Answer-EBL/VRM data
What Speed Indicators Should Provide Inputs to ARPA Equipment According to IMO? - Answer-The ship's
speed through water
Minimum Number of Targets an IMO Approved ARPA Must Track Simultaneously? - Answer-20
Lowest Range Scale IMO Requires ARPA Facilities to be Available On? - Answer-3 miles
IMO Standards for ARPA Data Display Visibility? - Answer-Should be visible to more than 1 observer in
light conditions
IMO Requirements for Past Positions Displayed by ARPAs? - Answer-All ARPAs can display both true and
relative past positions
What controls can be adjusted if known targets are not being detected on radar? - Answer-Gain,
suppressions, range scale
What factors contribute to the assessment of risk of collision? - Answer--Relative motion line
(CPA/TCPA)
-Aspect
-Error in calculations
When will a radar contact remain stationary on a relative motion radar display? - Answer-When it is on
the same course and speed as your vessel
If a radar contact is dead ahead and the range decreases without a change in bearing, what is the
estimated speed of the contact? - Answer-Dead in the Water (DIW)
If a radar contact is directly astern and the range decreases without a change in bearing, what is the
estimated speed of the contact? - Answer-15 knots
How can the closest point of approach (CPA) of a contact on a relative motion radar be determined? -
Answer-After marking the contact at least twice over a minute
What is a radar display called when North is always at the top of the screen? - Answer-Stabilized display
What inputs are needed to maintain a North-Up, True Motion display on radar? - Answer-Gyro course,
speed log
, Besides ARPA information, what should an ARPA user consider? - Answer--Limitations of the information
-Rules of the road
-Circumstances and external considerations
In restricted visibility, what should you avoid when altering course for a vessel forward of your beam? -
Answer-Avoid altering course to port except in overtaking situations
When two ARPA Equipped Ships Collide, What Is Typically True? - Answer-Both vessels are likely to be
found at fault
When Using an ARPA, What Should You Consider to Evaluate Displayed Information? - Answer-
Navigational constraints may require a target vessel to change course
What Information Is Least Dependent on ARPA Processing? - Answer-EBL/VRM data
What Speed Indicators Should Provide Inputs to ARPA Equipment According to IMO? - Answer-The ship's
speed through water
Minimum Number of Targets an IMO Approved ARPA Must Track Simultaneously? - Answer-20
Lowest Range Scale IMO Requires ARPA Facilities to be Available On? - Answer-3 miles
IMO Standards for ARPA Data Display Visibility? - Answer-Should be visible to more than 1 observer in
light conditions
IMO Requirements for Past Positions Displayed by ARPAs? - Answer-All ARPAs can display both true and
relative past positions
