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AIS STANDARD SEARCH AND RESCUE AIRCRAFT POSITION REPORT (MESSAGE 9)

This message should be used as a standard position report for aircraft involved in SAR operations. Stations other than aircraft involved in SAR operations should not transmit this message. The default reporting interval for this message should be 10 s.

 

Parameter

Number of bits

Description

Message ID

6

Identifier for Message 9; always 9

Repeat indicator

2

Used by the repeater to indicate how many times a message has been repeated. 0-3; 0 = default; 3 = do not repeat any more

User ID

30

MMSI number

Altitude (GNSS)

12

Altitude (derived from GNSS or barometric (see altitude sensor parameter below)) (m) (0-4 094 m) 4 095 = not available,
4 094 = 4 094 m or higher

SOG

10

Speed over ground in knot steps (0-1 022 knots)
1 023 = not available, 1 022 = 1 022 knots or higher

Position accuracy

1

1 = high (£10 m)
0 = low (>10 m)
0 = default

Longitude

28

Longitude in 1/10 000 min (±180°, East = positive (as per 2s complement), West = negative (as per 2s complement);
181 = (6791AC0h) = not available = default)

Latitude

27

Latitude in 1/10 000 min (±90°, North = positive (as per 2s complement), South = negative (as per 2s complement);
91 = (3412140h) = not available = default)

COG

12

Course over ground in 1/10 = (0-3 599). 3 600 (E10h) = not available = default; 3 601-4 095 should not be used

Time stamp

6

UTC second when the report was generated by the EPFS (0-59 or 60 if time stamp is not available, which should also be the default value
or 61 if positioning system is in manual input mode or 62 if electronic position fixing system operates in estimated (dead reckoning) mode
or 63 if the positioning system is inoperative)

Altitude sensor

1

0 = GNSS
1 = barometric source

Spare

7

Not used. Should be set to zero. Reserved for future use

DTE

1

Data terminal ready (0 = available 1 = not available = default)

Spare

3

Not used. Should be set to zero. Reserved for future use

Assigned mode flag

1

0 = Station operating in autonomous and continuous mode = default
1 = Station operating in assigned mode

RAIM-flag

1

RAIM flag of electronic position fixing device; 0 = RAIM not in use = default; 1 = RAIM in use

Communication state selector flag

1

0 = SOTDMA communication state follows
1 = ITDMA communication state follows

Communication state

19

SOTDMA communication state if communication state selector flag is set to 0, or ITDMA communication state if communication state selector flag is set to 1

Number of bits

168

 

 

 

(Source: Rec. ITU-R M.1371-5)