ARPA Flashcards
1
Q
List the ARPA card in the correct order
A
- Present range
- Present bearing
- Predicted CPA
- Predicted TCPA
- Calculated true course
- Calculated true speed
2
Q
3 considerations for CPA and TCPA in ARPA
A
- Visibility
- Traffic density
- Manoeuvrability of own vessel
3
Q
Why is it important to use radar in sea stabilised mode for collision avoidance?
A
- If there is current present the heading of other vessels will be shown more accurately and thus the aspect will be more accurate. Colregs are mainly based on aspect.
4
Q
What are 8 IMO requirements for ARPA?
A
- ARPA must be able to track at least 20 targets automatically and 10 manually.
- ARPA should be able to display history - minimum of 4 positions over at least 8 minutes
- ARPA should indicate lost targets
- ARPA should have a trial manoeuvre function
- Range and bearing info must be quickly available for objects appearing on an ARPA display.
- Data requirements are Target Range, Bearing, Predicted CPA, Predicted TCPA, True Course and True Speed
- ARPA data should be clearly visible to more than one person on the bridge during the day and at night.
- ARPA must provide laid down accuracy within 1 and 3 minutes.
5
Q
What are some ARPA alarms?
A
- A selected target breaches user defined CPA/TCPA limits
- A tracked target is lost
- An input failure (Gyro, speed etc.)
- A target enters the guard zone (that isn’t already being tracked)
- Picture freeze
6
Q
What is the order of information from ARPA?
A
- Target range, Bearing, Predicted CPA, Predicted TCPA, True course, True speed
7
Q
Name some problems with ARPA (6 factors)
A
- ARPA will not question any faulty data inputs from own vessel i.e speed, heading - this will change the vector triangle calculation therefore giving potentially dangerous incorrect data
- Range and bearing discrimination still exists
- Ice, small targets and floating objects may not appear and remain undetected
- False echoes may give rise to false situations
- Lost targets, in sea state or rain banks
- Target swap (when a target plotted by an ARPA loses its ‘tag’ to another passing vessel or static radar target)
- Over-reliance in the technology
8
Q
ARPA: Vessel RADAR & Plotting Aid Requirements
A
9
Q
Box Acquisition Phase
A
10
Q
ARPA Features
A
11
Q
Trial Manoeuvre Mode
A
12
Q
ARPA Performance Standards
A
13
Q
ARPA: ALARMS!!!
A
14
Q
Problems with ARPA
A