AIS - AUTOMATIC IDENTIFICATION SYSTEM | LATEST EXAM
QUESTIONS AND SOLUTIONS - VERIFIED ANSWERS 2026/2027
1. What does the abbreviation AIS stand for?
A. Automatic Interrogation System
B. Automated Information Service
C. Automatic Identification System
D. Advanced Integrated Signalling
ANSWER : C. Automatic Identification System
Explanation: AIS is the Automatic Identification System, a shipborne
VHF broadcast transponder system.
2. What is the primary purpose of AIS?
A. To improve safety of navigation by automatically exchanging
identity, position and other data between ships and shore
B. To replace radar for collision avoidance
C. To transmit weather forecasts to ships
D. To provide voice communication between ship and shore
ANSWER : A. To improve safety of navigation by automatically
exchanging identity, position and other data between ships and
shore
Explanation: AIS supports safety of life at sea, navigational efficiency
and protection of the marine environment by automatic data
exchange.
3. Which international convention makes the carriage of AIS
mandatory?
A. COLREG
B. STCW
C. MARPOL
D. SOLAS
ANSWER : D. SOLAS
Explanation: Carriage requirements for AIS are set out in SOLAS
Chapter V, Regulation 19.
Page 1 of 60
,4. In which radio band does AIS operate?
A. HF band
B. UHF satellite band
C. VHF maritime mobile band
D. MF band
ANSWER : C. VHF maritime mobile band
Explanation: AIS uses two dedicated channels in the VHF maritime
mobile band.
5. What is the frequency of AIS 1?
A. 162.025 MHz
B. 161.975 MHz
C. 156.800 MHz
D. 156.525 MHz
ANSWER : B. 161.975 MHz
Explanation: AIS 1 (channel 87B) operates on 161.975 MHz.
6. What is the frequency of AIS 2?
A. 156.650 MHz
B. 161.975 MHz
C. 157.100 MHz
D. 162.025 MHz
ANSWER : D. 162.025 MHz
Explanation: AIS 2 (channel 88B) operates on 162.025 MHz.
7. Which channel designations are used for AIS 1 and AIS 2?
A. 75 and 76
B. 13 and 14
C. 87B and 88B
D. 16 and 70
ANSWER : C. 87B and 88B
Explanation: AIS 1 is channel 87B and AIS 2 is channel 88B.
8. What is the channel spacing used by AIS?
A. 6.25 kHz
B. 25 kHz
C. 50 kHz
D. 12.5 kHz
ANSWER : B. 25 kHz
Explanation: AIS channels have a 25 kHz bandwidth.
Page 2 of 60
,9. Which modulation technique is used by AIS?
A. Quadrature amplitude modulation (QAM)
B. Audio frequency shift keying (AFSK)
C. Gaussian Minimum Shift Keying (GMSK)
D. Amplitude modulation (AM)
ANSWER : C. Gaussian Minimum Shift Keying (GMSK)
Explanation: AIS uses GMSK/FM modulation.
10. What is the data rate of the AIS VHF data link?
A. 9600 bits per second
B. 4800 bits per second
C. 19200 bits per second
D. 1200 bits per second
ANSWER : A. 9600 bits per second
Explanation: The AIS VHF data link operates at 9600 bit/s.
11. Which channel access scheme forms the basis of AIS?
A. Code Division Multiple Access (CDMA)
B. Polling by shore stations only
C. Time Division Multiple Access (TDMA)
D. Frequency Division Multiple Access (FDMA)
ANSWER : C. Time Division Multiple Access (TDMA)
Explanation: AIS is based on TDMA, with each station transmitting in
its own time slots.
12. How long is one AIS frame?
A. 6 minutes
B. 60 seconds
C. 10 seconds
D. 1 second
ANSWER : B. 60 seconds
Explanation: An AIS frame lasts one minute.
13. How many time slots are there per channel in one frame?
A. 1125
B. 4500
C. 2250
D. 1000
ANSWER : C. 2250
Explanation: Each channel has 2250 slots per one-minute frame.
Page 3 of 60
, 14. How many slots are available in total on both AIS channels per
frame?
A. 9000
B. 4500
C. 1125
D. 2250
ANSWER : B. 4500
Explanation: Two channels of 2250 slots give 4500 slots per frame.
15. What is the approximate duration of one AIS time slot?
A. 1 second
B. 10 milliseconds
C. 100 milliseconds
D. 26.67 milliseconds
ANSWER : D. 26.67 milliseconds
Explanation: 60 seconds divided by 2250 slots is about 26.67 ms.
16. How many bits can be carried in one AIS slot?
A. 512 bits
B. 168 bits
C. 128 bits
D. 256 bits
ANSWER : D. 256 bits
Explanation: A slot is 256 bit-times long, including ramp-up, training,
flags, CRC and guard bits.
17. Which system normally supplies the position data used by AIS?
A. Global Navigation Satellite System (GNSS)
B. Doppler log
C. Gyro compass
D. Echo sounder
ANSWER : A. Global Navigation Satellite System (GNSS)
Explanation: AIS obtains position and time from a GNSS receiver such
as GPS.
Page 4 of 60
QUESTIONS AND SOLUTIONS - VERIFIED ANSWERS 2026/2027
1. What does the abbreviation AIS stand for?
A. Automatic Interrogation System
B. Automated Information Service
C. Automatic Identification System
D. Advanced Integrated Signalling
ANSWER : C. Automatic Identification System
Explanation: AIS is the Automatic Identification System, a shipborne
VHF broadcast transponder system.
2. What is the primary purpose of AIS?
A. To improve safety of navigation by automatically exchanging
identity, position and other data between ships and shore
B. To replace radar for collision avoidance
C. To transmit weather forecasts to ships
D. To provide voice communication between ship and shore
ANSWER : A. To improve safety of navigation by automatically
exchanging identity, position and other data between ships and
shore
Explanation: AIS supports safety of life at sea, navigational efficiency
and protection of the marine environment by automatic data
exchange.
3. Which international convention makes the carriage of AIS
mandatory?
A. COLREG
B. STCW
C. MARPOL
D. SOLAS
ANSWER : D. SOLAS
Explanation: Carriage requirements for AIS are set out in SOLAS
Chapter V, Regulation 19.
Page 1 of 60
,4. In which radio band does AIS operate?
A. HF band
B. UHF satellite band
C. VHF maritime mobile band
D. MF band
ANSWER : C. VHF maritime mobile band
Explanation: AIS uses two dedicated channels in the VHF maritime
mobile band.
5. What is the frequency of AIS 1?
A. 162.025 MHz
B. 161.975 MHz
C. 156.800 MHz
D. 156.525 MHz
ANSWER : B. 161.975 MHz
Explanation: AIS 1 (channel 87B) operates on 161.975 MHz.
6. What is the frequency of AIS 2?
A. 156.650 MHz
B. 161.975 MHz
C. 157.100 MHz
D. 162.025 MHz
ANSWER : D. 162.025 MHz
Explanation: AIS 2 (channel 88B) operates on 162.025 MHz.
7. Which channel designations are used for AIS 1 and AIS 2?
A. 75 and 76
B. 13 and 14
C. 87B and 88B
D. 16 and 70
ANSWER : C. 87B and 88B
Explanation: AIS 1 is channel 87B and AIS 2 is channel 88B.
8. What is the channel spacing used by AIS?
A. 6.25 kHz
B. 25 kHz
C. 50 kHz
D. 12.5 kHz
ANSWER : B. 25 kHz
Explanation: AIS channels have a 25 kHz bandwidth.
Page 2 of 60
,9. Which modulation technique is used by AIS?
A. Quadrature amplitude modulation (QAM)
B. Audio frequency shift keying (AFSK)
C. Gaussian Minimum Shift Keying (GMSK)
D. Amplitude modulation (AM)
ANSWER : C. Gaussian Minimum Shift Keying (GMSK)
Explanation: AIS uses GMSK/FM modulation.
10. What is the data rate of the AIS VHF data link?
A. 9600 bits per second
B. 4800 bits per second
C. 19200 bits per second
D. 1200 bits per second
ANSWER : A. 9600 bits per second
Explanation: The AIS VHF data link operates at 9600 bit/s.
11. Which channel access scheme forms the basis of AIS?
A. Code Division Multiple Access (CDMA)
B. Polling by shore stations only
C. Time Division Multiple Access (TDMA)
D. Frequency Division Multiple Access (FDMA)
ANSWER : C. Time Division Multiple Access (TDMA)
Explanation: AIS is based on TDMA, with each station transmitting in
its own time slots.
12. How long is one AIS frame?
A. 6 minutes
B. 60 seconds
C. 10 seconds
D. 1 second
ANSWER : B. 60 seconds
Explanation: An AIS frame lasts one minute.
13. How many time slots are there per channel in one frame?
A. 1125
B. 4500
C. 2250
D. 1000
ANSWER : C. 2250
Explanation: Each channel has 2250 slots per one-minute frame.
Page 3 of 60
, 14. How many slots are available in total on both AIS channels per
frame?
A. 9000
B. 4500
C. 1125
D. 2250
ANSWER : B. 4500
Explanation: Two channels of 2250 slots give 4500 slots per frame.
15. What is the approximate duration of one AIS time slot?
A. 1 second
B. 10 milliseconds
C. 100 milliseconds
D. 26.67 milliseconds
ANSWER : D. 26.67 milliseconds
Explanation: 60 seconds divided by 2250 slots is about 26.67 ms.
16. How many bits can be carried in one AIS slot?
A. 512 bits
B. 168 bits
C. 128 bits
D. 256 bits
ANSWER : D. 256 bits
Explanation: A slot is 256 bit-times long, including ramp-up, training,
flags, CRC and guard bits.
17. Which system normally supplies the position data used by AIS?
A. Global Navigation Satellite System (GNSS)
B. Doppler log
C. Gyro compass
D. Echo sounder
ANSWER : A. Global Navigation Satellite System (GNSS)
Explanation: AIS obtains position and time from a GNSS receiver such
as GPS.
Page 4 of 60
