AIS message type

AIS message type 15: Interrogation

Requests a specific message from one or two other stations. What type 15 carries, who sends it, how often, and how to read it.

What type 15 is

Type 15 asks up to two stations to transmit a named message type. A type 3 is the usual response to an interrogation for a position report.

Protocol traffic. A type 3 is the usual reply.

The AIS message decoder reads the message type and sender MMSI of any sentence, including this one, but does not unpack the body of type 15.

Type	Name
1	Position report, scheduled (Class A)
2	Position report, assigned schedule (Class A)
3	Position report, response to interrogation (Class A)
4	Base station report
5	Static and voyage related data (Class A)
6	Binary addressed message
7	Binary acknowledge
8	Binary broadcast message
9	Standard SAR aircraft position report
10	UTC and date inquiry
11	UTC and date response
12	Addressed safety related message
13	Safety related acknowledgement
14	Safety related broadcast message
15	Interrogation
16	Assignment mode command
17	DGNSS broadcast binary message
18	Standard Class B equipment position report
19	Extended Class B equipment position report
20	Data link management message
21	Aid-to-navigation report
22	Channel management
23	Group assignment command
24	Static data report (Class B)
25	Single slot binary message
26	Multiple slot binary message with communications state
27	Long-range AIS broadcast message