VTS Navigation Systems 2 — Questions and Answers
Question 1: What does AIS stand for in the context of vessel traffic management?
- Automated Identification System (Correct answer)
- Automatic Information Service
- Auxiliary Integrated Sensor
- Advanced Intercept System
Correct answer: Automated Identification System
AIS (Automated Identification System) transmits vessel identity, position, course, and speed to other ships and VTS centers.
Question 2: A vessel reports its position as 'at anchor in the anchorage.' On radar, the VTS operator notices the vessel is slowly drifting. What is the most likely cause?
- The vessel is dragging anchor (Correct answer)
- Radar display calibration error
- The vessel is maneuvering under power
- Tidal current distortion of radar returns
Correct answer: The vessel is dragging anchor
A vessel at anchor that shows movement on radar is most likely dragging its anchor, which requires immediate VTS action.
Question 3: Which AIS message type is used to broadcast safety-related text messages to vessels?
- Message 14 (Correct answer)
- Message 1
- Message 21
- Message 4
Correct answer: Message 14
AIS Message Type 14 is the Safety Related Broadcast Message used to transmit text-based safety information to all vessels.
Question 4: What is the primary purpose of a VHF Direction Finding (VHF/DF) system in a VTS center?
- To determine the bearing of a transmitting vessel (Correct answer)
- To measure vessel speed
- To identify radar contacts
- To encrypt radio communications
Correct answer: To determine the bearing of a transmitting vessel
VHF/DF enables the VTS operator to determine the compass bearing from which a VHF transmission is originating, helping to locate vessels.
Question 5: On a radar display, what does a vessel's 'trail' or 'tail' indicate?
- The vessel's recent track history (Correct answer)
- Wind direction relative to the vessel
- The vessel's beam width on radar
- Clutter from wave returns
Correct answer: The vessel's recent track history
A radar trail or tail shows the recent path a vessel has traveled, helping the operator assess its course and speed over time.
Question 6: What is the significance of MMSI in a VTS context?
- It uniquely identifies a vessel for AIS and DSC communications (Correct answer)
- It specifies the vessel's maximum speed
- It indicates the vessel's cargo class
- It sets the VHF working channel
Correct answer: It uniquely identifies a vessel for AIS and DSC communications
The Maritime Mobile Service Identity (MMSI) is a unique nine-digit number that identifies a vessel in AIS transmissions and DSC distress calls.
Question 7: A radar target that shows no AIS correlation is called what in VTS terminology?
- A 'sleeping' or unmatched target (Correct answer)
- A ghost echo
- A SART contact
- A radar beacon
Correct answer: A 'sleeping' or unmatched target
A radar contact with no corresponding AIS signal is referred to as a sleeping or unmatched target, requiring investigation by the VTS operator.
VTS Navigation Systems 2
What does AIS stand for in the context of vessel traffic management?