ARPA - OOD Phase 1
You set your CPA and TCPA limits to 0.3 nm and 20 minutes. You have a contact that will have a CPA of
0.4 nm in 15 minutes, will you receive an alarm for this contact? Why - Answer-No. Both have to be
violated.
T or F: Hooking a contact when it first comes on your RADAR scope initiates the process for ARPA to
track the contact. - Answer-F
In a GPS denied environment, would ARPA or AIS be more useful? Why? - Answer--ARPA
-AIS is reliant on GPS.
T or F: You will get an alarm if you experience target swap in the rain. - Answer-F
Name 3 performance standards set by the International Maritime Organization (IMO) for ARPA. -
Answer--Tracking between 1-3 minutes
-Display 3 or 4 and 12 or 16
-Has to be visible by 2 people
-Warnings will not occur for target swap
-Accuracy of 2.7 nm (Settings)
You are operating in a sea stabilized display and note a contact has a true course of 090 degrees true
with a true speed of 1.1 kts. You know this object is a stationary buoy. What is the set and drift? -
Answer-270 degrees, 1.1 kts
Is it best to use true vectors or relative vectors to determine a contacts CPA? Why? - Answer--Relative
-Shows relative motion and see how close they will get to us (CPA).
, Describe the purpose of utilizing two guard zones on ARPA. - Answer-Redundancy for safety.
Describe 2 disadvantages of auto acquisition. - Answer--Could pick up choppy seas as a contact
-False echoes
-Alarms do not sound for each acquisition
What controls would you adjust if known targets were not being detected on your radar? - Answer--Gain
-Range
-Scale
Which of the following contributes to assessment of risk of collision? - Answer--The relative motion line
(CPA/TCPA)
-Aspect
-The amount of error in the calculations
A radar contact will remain stationary on a relative motion radar display only when it is... - Answer-On
the same course and speed as your vessel
You are underway at 10 kts. At 1800 you note a radar contact dead ahead at a range of 10 miles. At
1812, the contact is still dead ahead but at a range of 8 miles. The estimated speed of the contact is... -
Answer-Dead in the Water (DIW)
You are underway at 5 kts and see on your radar a contact 10 miles directly astern of you. 12 minutes
later, the same contact is 8 miles directly astern of you. What is the estimated speed of the contact? -
Answer-15 kts
You set your CPA and TCPA limits to 0.3 nm and 20 minutes. You have a contact that will have a CPA of
0.4 nm in 15 minutes, will you receive an alarm for this contact? Why - Answer-No. Both have to be
violated.
T or F: Hooking a contact when it first comes on your RADAR scope initiates the process for ARPA to
track the contact. - Answer-F
In a GPS denied environment, would ARPA or AIS be more useful? Why? - Answer--ARPA
-AIS is reliant on GPS.
T or F: You will get an alarm if you experience target swap in the rain. - Answer-F
Name 3 performance standards set by the International Maritime Organization (IMO) for ARPA. -
Answer--Tracking between 1-3 minutes
-Display 3 or 4 and 12 or 16
-Has to be visible by 2 people
-Warnings will not occur for target swap
-Accuracy of 2.7 nm (Settings)
You are operating in a sea stabilized display and note a contact has a true course of 090 degrees true
with a true speed of 1.1 kts. You know this object is a stationary buoy. What is the set and drift? -
Answer-270 degrees, 1.1 kts
Is it best to use true vectors or relative vectors to determine a contacts CPA? Why? - Answer--Relative
-Shows relative motion and see how close they will get to us (CPA).
, Describe the purpose of utilizing two guard zones on ARPA. - Answer-Redundancy for safety.
Describe 2 disadvantages of auto acquisition. - Answer--Could pick up choppy seas as a contact
-False echoes
-Alarms do not sound for each acquisition
What controls would you adjust if known targets were not being detected on your radar? - Answer--Gain
-Range
-Scale
Which of the following contributes to assessment of risk of collision? - Answer--The relative motion line
(CPA/TCPA)
-Aspect
-The amount of error in the calculations
A radar contact will remain stationary on a relative motion radar display only when it is... - Answer-On
the same course and speed as your vessel
You are underway at 10 kts. At 1800 you note a radar contact dead ahead at a range of 10 miles. At
1812, the contact is still dead ahead but at a range of 8 miles. The estimated speed of the contact is... -
Answer-Dead in the Water (DIW)
You are underway at 5 kts and see on your radar a contact 10 miles directly astern of you. 12 minutes
later, the same contact is 8 miles directly astern of you. What is the estimated speed of the contact? -
Answer-15 kts
