AIS Flashcards

1
Q
  1. What does SOTDMA stand for? (6)
A

Self-Organising Time Division Multiple Access

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2
Q
  1. What is the difference between a class A and a class B vessel? (4)
A

Class A is a vessel which it is mandatory to have AIS fitted to (commercial vessels over 3OOGT, cargo vessel >500GT, all passengers vessels). Class B is a non~mandatory fit vessel, vessels such as Fishing, leisure craft which have class B AIS equipment fitted

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3
Q
  1. State the three different types of information that is broadcasted (6)
A
  1. Static
  2. Dynamic
  3. Voyage Related
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4
Q
  1. How frequently is each of the above transmitted? (6)
A
  1. Every 6 minutes or on request
  2. 2” to 3 min - Dependent on ship speed and whether altering course
  3. Every 6 minutes or on request
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5
Q
  1. List two things that are safety related messages are NOT for (2)
A

Distress
Personal messages

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6
Q
  1. State three advantages of AIS over Radar (3)
A

It can see round corners
It gives immediate indication of vessel altering course
Targets do not get lost in clutter

…and there are other advantages

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7
Q
  1. Why should the OOW not over rely on AIS information for collision avoidance? (3)
A

Information is provided from another vessel’s instruments, which we cannot check to be correct. CPA and TCPA is from a different source and could be incorrect. The ColRegs are based on visual and radar detection.

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8
Q
  1. What 3 modes of operation should AIS be able to work in? (3)
A

Autonomous and Continuous
Assigned
Polled

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9
Q

List the elements of class A data

A

STATIC DATA:
* Call sign and name
* IMO number
* Length and beam
* Type of ship
* Location of GPS antenna

DYNAMIC DATA:
* Ship position
* Position time in UTC
* COG e SOG
* Heading
* Navigational Status
* Rate of turn

VOYAGE DATA
* Draught
* Hazardous cargo type
* Destination and ETA

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10
Q

State the differences between AIS Class A and B

A

Clas B is nearly identical to class A but:
* Does not transmit IMO number
* Does not transmit destination and ETA
* Does not transmit navigational status
* Does not transmit navigationel status
* Does not transmit rate of turn
* Does not transmit draught
* receive, but does not transmit, safety and text messages

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