ARPA Written Exam – OOD | Latest 2025/ 2026 Update | Questions and Answers | 100% Verified Solutions | GRADED A

ARPA Written Exam – OOD | Latest 2025/ 2026 Update | Questions and Answers | 100% Verified Solutions | GRADED A …… Question: What controls would you adjust if known targets were not being detected on your radar? Answer: Gain, suppressions + range scale Question: What contributes to assessment of risk of collision? Answer: -relative motion line (CPA/TCPA) -Aspect -the amount of error in calculations Question: A radar contact will remain stationary on a relative motion radar display only when it is? Answer: On the same course + speed as your vessel Question: 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 bu at a range of 8 miles. The estimated speed of the contact is ________. Answer: Dead in the Water (DIW) Question: 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 Question: The closest point of approach (CPA) of a contact on a relative motion radar may be determined: Answer: after the contact has been marked at least twice over a period of at least a minute Question: A radar display in which the orientation of the display is fixed so that North is always at the top of the screen is called a/an Answer: Stabilized display Question: What inputs are required to maintain a North-Up, True Motion display? Answer: Gyro course + speed log Question: In addition to ARPA information, an ARPA user should take into account Answer: -the limitations of that information -rules of the road -circumstances of the situation including external considerations Question: In restricted visibility what should you avoid when altering course for a vessel forward of your beam that you cannot see visually? Answer: Altering course to port except in overtaking situations Question: When two ARPA equipped ships collide, which of the following is typically true? Answer: both vessels are likely to be found at fault Question: When using an ARPA, what should you consider in order to evaluate the information displayed? Answer: Navigational constraints may require a target vessel to change course Question: What information is least dependent of ARPA processing? Answer: EBL/VRM data Question: According to IMO, log and speed indicators providing inputs to ARPA equipment should be capable of providing: Answer: the ship's speed through water Question: What is the minimum number of targets that an IMO approved ARPA must track simultaneously? Answer: 20 Question: What is the lowest range scale that IMO requires ARPA facilities to be available on? Answer: 3 miles Question: According to IMO standards, the ARPA data display: Answer: should be visible to more than 1 observer in conditions of light normally Question: Regarding the IMO requirements for past positions: Answer: all ARPAs can display both true + relative past positions Question: IMO requires ARPA to operate in relative motion with Answer: either north-up, head-up or course-up display Question: According to IMO performance standards, what should an ARPA do to improve the standard of collision avoidance at sea? Answer: ARPA should reduce the workload of observers by automatically providing information Question: The ARPA facilities should be available on at least the following range scales: Answer: 3 or 4 miles and 12 or 16 miles Question: List 2 conditions needed for +/- steady state tracking Answer: -ownship maintains course + speed -target maintains course + speed Question: Which of the following is NOT a required operational warning on ARPA's? A. Lost Target B. Automatically acquired target C. CPA/TCPA - Close Quarter Warnings D. Guard Rings + Zones Answer: Automatically acquired target Question: The Navlines displayed on an ARPA Answer: will drift when ARPA is sea-stabilized Question: Gradual alternations of course will help the ARPA process data faster and provide more accurate information Answer: FALSE Question: When observing a target's past positions in TM what information can be quickly "gleamed"? Answer: target has changed course Question: Watchstanders can measure error in ARPA presented information by using Answer: a plotting sheet or grease pencil plot on a reflection plotter Question: You observe a target visually dead ahead but it is displayed on your radar at 5 degrees to starboard of the heading flash. How would you correct this? Answer: Check the scanner for antenna misalignment Question: When an ARPA-tracked target maneuvers: Answer: first indication of a maneuver will probably be seen on a persistence or afterglow feature if your ARPA has one Question: Regarding ARPA errors, which of the following is true? Answer: Relying on ARPA information can be dangerous unless the user understands the system will enough to evaluate its limitations Question: The vector displayed after 3 minutes of steady state tracking Answer: represents the targets probable past projected into the future Question: When operating a RADAR in fog, it is possible to have a limited effective range? Answer: TRUE Question: True or False: The ability of radar to detect objects is unaffected by weather conditions Answer: False Question: True or False: When operating a RADAR in fog, RADAR ranges are less accurate? Answer: False Question: Name the radar error that would cause the multiple targets to appear with the same bearing (090) at equipment-distant .5 nm, 1 nm, 1.5 nm Answer: Multiple echoes Question: True or False: You will get an alarm if target swap has occurred Answer: False Question: If CPA/TCPA alarm is continually going off what should you do? Answer: Adjust the limited to reflect the conditions Question: What input to an ARPA is needed for sea stabilized information? Answer: Radar input, gyro heading, and speed through the water Question: What do ground stabilized true vectors intended to represent? Answer: recent track of a target's motion over the ground projected into the future Question: When using navlines for navigation, which stabilization method should be used? Answer: Ground Question: When can TRIAL MANEUVER mode display inaccurate information? Answer: when ARPA (vectors) are ground stabilized Question: When using a course-up stabilized display Answer: the heading flasher does not move when you change course Question: What suppression should be used with heavy cloud cover and storms? Answer: Rain (FTC) Question: True or False: AIS provides the other vessel's identity, dimensions and navigational status regardless of visibility Answer: True Question: True or False: In the true presentation history display of past positions, ARPA provides a quick visual check to determine if a vessel has changed course Answer: True Question: If your speed input is incorrect, what effect would it have on your ARPA data? Answer: True vectors would be incorrect Question: Cases in which your ARPA will alarm Answer: -target initially detected in guard zone -tracked target who violates CPA/TCPA limits -lost target -tracked target who violates BCT/BCR -ARPA failure -input loss (GPS, speed, gyro) Question: Your ARPA has 2 guard "trip wire" ring alarms. What is the purpose of the inner guard ring? Answer: Warn of small targets that are initially detected closer than the outer guard ring Question: The radar control most helpful in reducing sea return situation at close ranges is the Answer: sensitivity time control (STC) Question: When ARPA's are used in sea stabilized mode with true tracks, data relating to own ship's motion is fed to the ARPA from the Answer: speed log and gyro Question: When your ship is in a cross current, the Navlines on your ARPA screen will remain stationary, or near stationary when you operate in Answer: Ground stabilized mode Question: Which warning is required by the IMO performance standards? Answer: A warning any time a target closes to a designated range or transits a zone, chosen by the observer Question: Provided a target is not subject to target swap, the ARPA should continue to track an acquired target which is clearly distinguishable on the display for __________ Answer: 5 out of 10 consecutive scans Question: Which of the following is NOT a commonly used term for ARPA's target persistence or afterglow? Answer: A. Echo trails B. True wakes C. Target trails D. History dots History dots Question: List 4 conditions that would cause a fixed target (I.e Light House) to appear to have a true speed of more than 0 Answer: -Centroid shift -Current -Incorrect speed input on your ARPA -Target swap