Details of file format and data values provided in standard AIS data samples.
Spire Maritime AIS data samples are normally provided in CSV format with data fields as listed in the table of data fields below.
Different AIS Messages:
It is important to understand the data and in particular that the file contains data from 2 different type of AIS messages. AIS positions messages that report the position, speed, heading, rate of turn and status of vessels and AIS static voyage messages that report identity, type, size and voyage information.
These 2 types of data are linked only by the vessels MMSI number which is used as the vessel identifier for both.
Message Types 1, 2, 3, 18, 19, 27 are position messages and contain values in the position related fields.
Message Types 5 & 24 are static voyage messages and contain values in the static details and voyage related fields.
To identify the Name, IMO number or type of ships related to the AIS Position reports, the MMSI number must be used to join together the 2 different sets of AIS data.
IE if position reports are recorded against MMSI 636018333 in AIS message type 1 then the IMO and name of that vessel is discovered by looking for AIS message type 5 reported using the same MMSI number as shown below.
Table showing the distribution of values in key fields from different AIS messages
AIS Data Sample File Column Descriptions:
|created_at||date||ISO 8601 formatted timestamp in UTC of the time the vessel record was created|
|timestamp||string||ISO 8601 formatted timestamp in UTC of the time the AIS message was transmitted|
AIS message type
1, 2, 3, 5, 18, 19, 24, 27
AIS message types are explained in more details here
The Maritime Mobile Service Identity of the vessel transmitting the AIS message
000000000 - 999999999
Vessel latitude in degrees
(North = positive, South = negative)
range -90 to +90
Vessel longitude in degrees
(East = positive, West = negative)
range = -180 to +180
Vessel speed over ground represented in knots
0 - 102.2 knots, 102.3 (not available)
Vessel course over ground in degrees
0 - 359.9 degrees, 360.0 (not available)
Vessel true heading in degrees
0 - 359 degrees, 511 (not available)
Vessel rate of turn
-127 - 127; -128 (not available)
IMO number of the ship
Unique International Maritime Organization number for the vessel that stays with the ship for it's life
valid values 7 digit number
Vessel call sign
Vessel draught represented in 1/10 meters
0.1 - 255, 0 (not available; default)
Vessel ship and cargo type code
Some common values:
30 (fishing vessel), 52 (tug boat), 70 (cargo/fishing ship)
more information on determining the ship type is detailed here
Vessel length extracted from ship dimensions to_bow and to_stern in meters
Vessel width extracted from ship dimensions to_port and to_starboard in meters
Vessel estimated time of arrival as entered by the captain, represented in ISO 8601 format
Month: 1 - 12, 0 (not available; default); Day: 1 - 31, 0 (not available; default); Hour: 0 - 23, 24 (not available; default); Minute: 0 - 59, 60 (not available; default)
Vessel destination as entered by the vessel captain
Vessel navigation status
Some common values:
0 (under way using engine), 1 (at anchor), 3 (restricted maneuverability), 7 (engaged in fishing), 15
Vessel maneuver code
0 (not available; default), 1 (not engaged in special maneuver), 2 (engaged in special maneuver)
Vessel GPS geo location accuracy in meters
1 (high, <=10 meters); 0 (low, >10 meters, default)
How the message was captured
satellite or terrestrial or dynamic
|to_bow||integer||Distance from AIS transponder to the bow side edge in meters (Hull dimension A)|
|to_stern||integer||Distance from AIS transponder to the stern side edge in meters (Hull dimension B)|
|to_port||integer||Distance from AIS transponder to the port side edge in meters (Hull dimension C)|
|to_starboard||integer||Distance from AIS transponder to the starbord side edge in meters (Hull dimension D)|