AIS Flashcards
- What does SOTDMA stand for? (6)
Self-Organising Time Division Multiple Access
- What is the difference between a class A and a class B vessel? (4)
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
- State the three different types of information that is broadcasted (6)
- Static
- Dynamic
- Voyage Related
- How frequently is each of the above transmitted? (6)
- Every 6 minutes or on request
- 2” to 3 min - Dependent on ship speed and whether altering course
- Every 6 minutes or on request
- List two things that are safety related messages are NOT for (2)
Distress
Personal messages
- State three advantages of AIS over Radar (3)
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
- Why should the OOW not over rely on AIS information for collision avoidance? (3)
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.
- What 3 modes of operation should AIS be able to work in? (3)
Autonomous and Continuous
Assigned
Polled
List the elements of class A data
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
State the differences between AIS Class A and B
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