ETO Navigation Electronics & GMDSS 2 — Questions and Answers
Question 1: What does AIS stand for in the context of marine navigation equipment?
- Automated Identification System
- Automatic Information System
- Automated Integrated System
- Automatic Identification System (Correct answer)
Correct answer: Automatic Identification System
AIS stands for Automatic Identification System; it automatically broadcasts vessel identity, position, speed, and course data to nearby ships and shore stations via VHF.
Question 2: On which VHF channels does Class A AIS operate for its transmissions?
- Channels 13 and 16
- Channels 70 and 77
- Channels 87B (161.975 MHz) and 88B (162.025 MHz) (Correct answer)
- Channels 16 and 22A
Correct answer: Channels 87B (161.975 MHz) and 88B (162.025 MHz)
Class A AIS transmits alternately on VHF channels 87B (161.975 MHz) and 88B (162.025 MHz), which are internationally designated solely for AIS use.
Question 3: Which radar frequency band provides the best target resolution for close-range navigation in congested waters?
- S-band (2-4 GHz)
- X-band (9-10 GHz) (Correct answer)
- L-band (1-2 GHz)
- C-band (4-8 GHz)
Correct answer: X-band (9-10 GHz)
X-band radar (9-10 GHz) uses shorter wavelengths that produce superior target discrimination and range resolution, making it the preferred band for coastal and harbor navigation.
Question 4: What is the primary function of ECDIS aboard a vessel?
- Electronic Chart Display and Information System used as an approved navigation system (Correct answer)
- Emergency Communication and Distress Information System for GMDSS
- Electronic Course and Distance Indicator System for autopilot
- Engine Control and Display Information System for propulsion monitoring
Correct answer: Electronic Chart Display and Information System used as an approved navigation system
ECDIS (Electronic Chart Display and Information System) displays official Electronic Navigational Charts and integrates position, radar overlay, and route planning data as an approved replacement for paper charts.
Question 5: What does the ARPA CPA/TCPA alarm warn the officer of the watch about?
- A radar contact that has disappeared from the screen
- A tracked target whose closest point of approach or time to CPA falls below preset alarm thresholds (Correct answer)
- A malfunction in the ARPA processor unit
- An AIS target that is not correlated with a radar echo
Correct answer: A tracked target whose closest point of approach or time to CPA falls below preset alarm thresholds
The CPA/TCPA alarm activates when ARPA calculates that a tracked target will pass within the preset minimum CPA distance or within the set TCPA time, alerting the officer to a potential collision risk.
Question 6: Which data must be manually entered into a Class A AIS transponder by the bridge crew?
- Speed over ground and course over ground
- GPS position fix
- Destination, ETA, draught, and other voyage-related data (Correct answer)
- Wind speed and direction
Correct answer: Destination, ETA, draught, and other voyage-related data
Voyage-specific information such as destination port, estimated time of arrival, and draught must be manually entered into the AIS transponder, while position and speed are fed automatically from connected sensors.
Question 7: What does ARPA stand for as fitted on modern navigational radar systems?
- Automatic Radar Plotting Aid (Correct answer)
- Advanced Radar Position Analysis
- Automated Route Planning Algorithm
- Automatic Route and Position Aid
Correct answer: Automatic Radar Plotting Aid
ARPA (Automatic Radar Plotting Aid) automatically acquires, tracks, and computes the CPA and TCPA of radar targets to assist officers with collision avoidance decisions.
ETO Navigation Electronics & GMDSS 2
What does AIS stand for in the context of marine navigation equipment?