VTS Navigation Systems 4 — Questions and Answers
Question 1: What is a Traffic Separation Scheme (TSS) and what is its primary function?
- A routing measure that separates opposing vessel traffic streams to reduce collision risk (Correct answer)
- A system for managing radio frequency assignments in a port
- An AIS-based vessel scheduling tool
- A radar zone that triggers automatic alarms
Correct answer: A routing measure that separates opposing vessel traffic streams to reduce collision risk
A TSS is an IMO-adopted routing measure that organizes one-way traffic lanes to separate vessels traveling in opposite directions and reduce collision risk.
Question 2: In a VTS area, a vessel is observed making a U-turn inside a TSS separation zone. What should the VTS operator do first?
- Contact the vessel and advise that maneuvering in the separation zone is prohibited under COLREGS Rule 10 (Correct answer)
- Immediately notify the Coast Guard for enforcement action
- Log the incident but take no immediate action
- Broadcast a general warning to all traffic in the area
Correct answer: Contact the vessel and advise that maneuvering in the separation zone is prohibited under COLREGS Rule 10
COLREGS Rule 10 prohibits vessels from entering the separation zone except in emergencies, so the VTS operator should first contact and advise the vessel.
Question 3: What technology does Differential GPS (DGPS) use to improve position accuracy?
- A reference station with a known position that broadcasts corrections to GPS errors (Correct answer)
- Additional satellites in geostationary orbit
- Onboard inertial navigation system cross-checks
- Multi-antenna signal averaging
Correct answer: A reference station with a known position that broadcasts corrections to GPS errors
DGPS uses a land-based reference station at a precisely known location to calculate GPS errors and broadcast correction signals to nearby receivers.
Question 4: Which COLREGS rule specifically addresses vessels' responsibilities in Traffic Separation Schemes?
- Rule 10 (Correct answer)
- Rule 13
- Rule 18
- Rule 5
Correct answer: Rule 10
COLREGS Rule 10 covers conduct of vessels in Traffic Separation Schemes, including requirements for joining, leaving, and crossing separation lanes.
Question 5: A vessel reports its position by latitude and longitude, but the position plots in the middle of land on the VTS chart. What is the most likely explanation?
- The vessel transposed or misread its GPS coordinates (Correct answer)
- The VTS chart is outdated
- GPS signal is blocked by terrain
- The vessel is using a different map projection
Correct answer: The vessel transposed or misread its GPS coordinates
A position that plots on land most commonly results from the vessel transposing digits or misreading its GPS display when making the report.
Question 6: What is the purpose of an Electronic Chart Display and Information System (ECDIS) in a VTS center?
- To display digital nautical charts integrated with sensor data such as AIS, radar, and GPS (Correct answer)
- To automatically file voyage plans for arriving vessels
- To replace VHF radio communications with digital messaging
- To manage vessel scheduling and berth assignments
Correct answer: To display digital nautical charts integrated with sensor data such as AIS, radar, and GPS
ECDIS integrates official electronic charts with real-time AIS, radar, and positioning data, giving VTS operators a comprehensive situational awareness picture.
Question 7: What is the key difference between a vessel's 'course over ground' (COG) and its 'heading'?
- Heading is the direction the bow points; COG is the actual direction of travel accounting for current and wind (Correct answer)
- COG is the compass bearing to the destination; heading is the actual direction of travel
- Heading accounts for magnetic variation; COG does not
- They are identical terms used interchangeably in VTS
Correct answer: Heading is the direction the bow points; COG is the actual direction of travel accounting for current and wind
Heading is the direction the vessel's bow points, while COG reflects the actual path made good through the water, which differs due to current and leeway.
VTS Navigation Systems 4
What is a Traffic Separation Scheme (TSS) and what is its primary function?