This message allows the communication of a vessels intended route to other vessels and shore stations.
The rules for broadcasting this message are the following
a) Only broadcast when the vessel is following an activated route.
b) The route must be broadcast every six minutes, due to what is stated in ITU-R M.1371-4 (§4.2.1) regarding sending interval for voyage related information.
c) On route activation the route must be broadcast.
d) When active waypoint changes the route must be broadcast.
e) On route deactivation, or when a route is completed, an empty message with no waypoints must be sent to indicate that the vessel is not following an intended route.
The broadcast waypoints must start with the current active waypoint and include up to the 15 following waypoints, giving a maximum of 16 waypoints.
Broadcasting 16 waypoints will result in a 5-slot message. It is recommended to avoid messages with more than 3 slots, equivalent to no more than 8 waypoints.
Jens Kristian Jensen
Danish Maritime Authority
JKJ@dma.dk [1]
Every 6 minutes and on active route change
Table 2.1
Intended route (broadcast)
Parameter | No. Of bits | Description |
Message ID | 6 | Identifier for Message 8; always 8. |
Repeat Indicator | 2 | Used by the repeater to indicate how many times a message has been repeated. |
Source ID | 30 | MMSI number of source station. |
Spare | 1 | Not used. Set to zero. |
IAI | 16 | DAC = 219; FI = 1 |
ETA active WP |
| The ETA at the active waypoint (first waypoint). For a cancellation of active route, the default values can be used. |
UTC Month | 4 | 1 - 12 |
UTC Day | 5 | 1 - 31 |
UTC Hour | 5 | 0 - 23 |
UTC Minute | 6 | 0 - 59 |
Duration | 18 | Minutes from ETA at active waypoint to ETA at the last broadcast waypoint. The duration allows for the calculation of an average intended speed on the broadcast route. 0 = not available = default |
Number of Waypoints | 5 | Number of Waypoints 1 - 16 0 = no active route = cancel route 17 - 31 (not used) |
Waypoints | n x 55 | Variable number of waypoints 0 – 16 (55 bit each), refer to table 2.2. |
Spare |
| Not used. Set to zero. |
Total | 99 – 979 | Occupies 2 – 5 slots. 1 - 4 waypoints = 2 slots 5 - 8 waypoints = 3 slots 9 - 12 waypoints = 4 slots 13 – 16 waypoints = 5 slots |
Table 2.2
Waypoints
Parameter | No. Of bits | Description |
|---|---|---|
WP Longitude | 28 | Longitude in 1/10,000 min, ±180 degrees as per 2's complement (East = positive, West = negative). |
WP Latitude | 27 | Latitude in 1/10,000 min, ±90 degrees as per 2's complement (North = positive, South = negative). |
See http://enav.frv.dk/ais_route_suggestion.pdf [2] for usage and portrayal details.
