IALA

Application acknowledgement to an addressed binary message

Details:

 Replacing by DAC 1 FI 1 (warning older AIS stations could still use DAC 1 FI 1)

Parameters Number of bits Description
Message ID 6 Identifier for Message 6; always 6
Repeat indicator 2 Used by the repeater to indicate how many times a message
has been repeated. See § 4.6.1, Annex 2; 0-3; 0 = default;
3 = do not repeat any more
Source ID 30 MMSI number of source station
Sequence number 2 0-3; see § 5.3.1, Annex 2
Destination ID 30 MMSI number of destination station
Retransmit flag 1 Retransmit flag should be set upon retransmission:
0 = no retransmission = default; 1 = retransmitted
Spare 1 Not used. Should be zero
DAC 10 International DAC = 110 = 00000000012
FI 6 Function identifier = 510 = 0001012
DAC code of received
FM
10 Recommended to be spare
FI code of received FM 6
Text sequence number 11 Sequence number in the message being acknowledged as
properly received
0 = default (no sequence number)
1-2 047 = sequence number of received FM
AI available 1 0 = received but AI not available
1 = AI available
AI response 3 0 = unable to respond
1 = reception acknowledged
2 = response to follow
3 = able to respond but currently inhibited
4-7 = spare for future use
Spare bits 49 Not used, should be set to zero, reserved for future use
Total number of bits 168 The resulting Message 6 occupies 1 slot