This message is primarily intended for long-range detection of AIS Class A and Class B “SO” equipped vessels (typically by satellite). This message has similar content to Messages 1, 2, and 3, but the total number of bits has been compressed to allow for increased propagation delays associated with long-range detection. Note there is no time stamp in this message. The receiving system is expected to provide the time stamp when this message is received.
|
Parameter |
Bits |
Description |
|---|---|---|
| Message ID | 6 | Identifier for this message; always 27 |
| Repeat indicator | 2 | Always 3 |
| User ID | 30 | MMSI number |
| Position accuracy | 1 | As defined for Message 1 |
| RAIM flag | 1 | As defined for Message 1 |
| Navigational status | 4 | As defined for Message 1 |
| Longitude | 18 | Longitude in 1/10 min (±180°, East = positive (as per 2’s complement), West = negative (as per 2’s complement)
181° (1A838h) = position older than 6 hours or not available = default) |
| Latitude | 17 |
Latitude in 1/10 min (±90°, North = positive (as per 2’s complement), South = negative (as per 2’s complement) 91° (D548h) = position older than 6 hours or not available = default) |
| SOG | 6 |
Knots (0-62); 63 = not available = default |
| COG | 9 |
Degrees (0-359); 511 = not available = default |
| Position Latency | 1 |
0 = Reported position latency is less than 5 seconds; 1 = Reported position latency is greater than 5 seconds = default |
| Spare | 1 |
Set to zero, to preserve byte boundaries |
| Total Number of bits | 96 |