Learn about MSI broadcasts as Inmarsat SafetyNET essentials, including message formatting, monitoring, EGC SafetyNET logs, and quality control for maritime safety and compliance.
EGC messages include instructions to the LES for processing MSI in the form of a special address header that consists of five (or six) C-codes as described below.
Message Formatting and C Codes
In order for a message to be correctly processed, it must always consist of data conforming to C codes “1” to “5“. Additionally, C code “0” shall be used when required by the service provider.
1 C0 Ocean Region code – 1 digit (when required):
- 0 – Atlantic Ocean Region – West;
- 1 – Atlantic Ocean Region – East;
- 2 – Pacific Ocean Region;
- 3 – Indian Ocean Region;
- 9 – all ocean regions (Note: availability of C0 = 9 should be checked with LES operator or service provider).
2 C1 priority code – 1 digit code.
3 C2 service code – 2 digit code.
4 C3 address code – 2, 4, 10 or 12 alphanumeric code.
5 C4 repetition code – 2 digit code.
6 C5 presentation code – normally a 2 digit code.
The syntax of the special address header in relation to the exact number of digits and/or alphanumeric characters, and to the spaces between each C code, is critical and must conform to the format required by the LES or service provider used.
C Codes | |||||
---|---|---|---|---|---|
C0 Ocean Region code (when required) | C1 Priority code | C2 Service code | C3 Address code | C4 Repetition code (See Understanding Inmarsat SafetyNET: A Vital Tool for Maritime Safety“Repetition codes (C4)”) | C5 Presentation code |
1 digit code | 1 digit code | 2 digit code | 2, 4, 10 or 12 alphanumeric code | 2 digit code | Normally a 2 digit code |
0 – AOR-W 1 – AOR-E 2 – POR 3 – IOR 9 – All Ocean Regions Subject to availability through LES or service provider.x | 1 – Safety 2 – Urgency 3 – Distress | 00 – All ships (general call) | 2 digit – 00 (All ships) | Category (a) – for EGC messages to be repeated a finite number of times. Category (b) – for EGC messages to be repeated at specified intervals until cancelled by the MSI provider. | 00 |
04 – Navigational, Meteorological or Piracy warning to a rectangular area | 12 alphanumeric rectangular area adress: D1 D2 N(S) D3 D4 D5 E(W) D6 D7 D8 D9 D10 | ||||
13 – Navigational, Meteorological or Piracy Coastal warning | 4 alphanumeric coastal warning area address: X1 X2 B1 B2 | ||||
14 – Shore-to-Ship Distress Alert to a circular area | 10 alphanumeric circular area adress: D1 D2 N(S) D3 D4 E(W) M1 M2 M | ||||
24 – Navigational, Meteorological or Piracy warning to a circular area | 10 alphanumeric circular area adress: D1 D2 N(S) D3 D4 E(W) M1 M2 M3 | ||||
31 – NAVAREA/METAREA warning, MET Forecast or Piracy warning to NAVAREA/METAREA | 2 digit – NAVAREA/METAREA number | ||||
34 – SAR Coordination to a rectangular area | 12 alphanumeric rectangular area adress: D1 D2 N(S) D3 D4 D5 E(W) D6 D7 D8 D9 D10 | ||||
44 – SAR Coordination to a circular area | 10 alphanumeric circular area adress: D1 D2 N(S) D3 D4 E(W) M1 M2 M3 |
SafetyNET messages are stored at the LES until transmitted the appropriate number of times, as specified by the C4 code, although the MSI provider may also cancel a message at any time by sending an appropriate cancellation message to the LES.
Cancellation procedure may vary between different LESs or service providers. Detailed operational procedure is contained in the instructions on sending EGC broadcast given to the MSI providers after registration with the LES operator or service providers.
Messages destined for areas of satellite overlap that are required to be transmitted through more than one Satellite, should be sent to more than one LES (i. e. one in each satellite ocean region) to ensure they are received by all intended ships. This may require co-ordination with adjacent NAVAREA/METAREA and other MSI providers. In an area of overlap coverage from two or three ocean region satellites, distress alert relays and urgency warnings will be broadcast over all satellites which cover the affected region.
Scheduled broadcasts are made over nominated satellites and at specified times, as allocated by the IMO International SafetyNET Co-ordinating Panel. These schedules are published in national nautical publications and the IMO Master Plan of Shore-Based Facilities for the GMDSS, as amended.
MSI providers shall adhere to their published scheduled broadcast times to facilitate reception of messages.
Monitoring of MSI Broadcasts
In order to ensure the integrity of the MSI being broadcast, MSI providers must monitor the broadcasts which they originate in accordance to IMO resolution A.706(17), as amended. Monitoring is especially important in a highly automated system, which is dependent on careful adherence to procedure and format.
This shall be accomplished by the installation of an EGC receiver to enable each MSI provider to:
- check that the message has been broadcast;
- confirm that the message is received correctly;
- ensure that cancellation messages are properly executed, and;
- observe any unexplained delay in the message being broadcast.
EGC receivers only display or print messages on the first occasion they are received. Therefore, in order for MSI providers to confirm that all messages in force are still being transmitted by the LES, and that cancelled messages are no longer being transmitted, the EGC receiver used by the MSI provider to monitor their SafetyNET broadcasts should be powered down (including the transceiver), and re-booted at regular intervals, where ever this is possible.
Alternatively, MSI providers should consult their equipment supplier for specialist EGC monitoring software which would not require the MES to be re-booted.
EGC SafetyNET Log
All Inmarsat-C and mini-C MESs capable of receiving MSI, have an EGC SafetyNET Log, which contains information on all SafetyNET messages received by the terminal.
Example of an EGC SafetyNET Log | |||||||
---|---|---|---|---|---|---|---|
Message Number | LES | Service | Priority | Rec Date & Time | Size | Seq. No | Routeing |
10022405.egc | 321 | MET/NAV Warning/Forecast | Safety | 10-02-24 03:31 | 2263 | 1605 | Prn+Mem |
10022402.egc | 321 | SAR Coordination | Urgency | 10-02-24 03:02 | 1506 | 1604 | |
10022401.egc | 322 | Coastal Warning/Forecast | Safety | 10-02-23 02:56 | 269 | 9154 | |
10022302.egc | 304 | Distress Alert Relay | Distress | 10-02-23 20:44 | 769 | 691 | |
10022305.egc | 317 | NAV Warning | Safety | 10-02-23 19:41 | 819 | 8318 | |
10022302.egc | 322 | MET Warning | Safety | 10-02-23 19:35 | 2358 | 9150 |
This information includes:
- Message number: Generated by the terminal.
- LES: ID of the LES which broadcast the message.
- Service: The MES software translates the C2 service code used in the message address and displays a short title for the particular type message service.
- Priority: The MES software translates the C1 priority code used in the message address and displays the appropriate Priority. This could be either; Safety, Urgency or Distress.
- Rec Date & Time: The date time group YY-MM-DD HH:mm of when the message was received.
- Size: Usually in number of bits or characters.
- Seq. No: The unique message sequence or reference number allocated to the message by the addressed LES.
- Routing: Message routeing (memory or memory and printer) – set up by the MES operator or a mandatory routeing for Urgency and Distress priority messages.
Quality Control of MSI Broadcasts
Misuse of C-codes. Monitoring of MSI broadcasts is a vital tool to show instances of misuse of C1 (priority), C2 (service) and C4 (repetition) codes and other technical or operational problems in connection with preparing and broadcasting EGC messages. Misuse of C-codes results in incorrect understanding of MSI services and types of message, multiple reception of unwanted messages received on ships and delay in receiving vital information.
Improper use of C1 priority codes
This refers mainly to the use of service code C2 = 14 “Ship-to-Shore distress alerts” which require using C1 = 3 Distress priority code only. Problems are caused when the service code C1 = 2 is used by mistake, as in the following example.
When C1 = 2 is erroneously used in conjunction with C2 = 14, the header of the message received on a ship is displayed and printed as:
LES xxx – MSG 1210 – Distress Urgent Call to Area: 14N 66W 300 – PosOK, where:
- LES xxx – ID of the LES;
- MSG 1210 – message number;
- Distress Call to Area – decoding of service C2 = 14;
- Urgent – decoding of priority C1 = 2;
- 14N 66W 300 – circular position the message was sent to, where 14N 66W – centre of the circle and 300 is radius of the circle in nautical miles, and;
- PosOK – indicator that the MES‘s position status is valid or the position was updated within the last 12 hours.
The message header contains reference to two different priorities at the same time – Distress and Urgent (the same problem may be evident in the EGC log or message list), which misleads mariners about the message importance and its content. This is an important issue, particularly for non-SOLAS users, where an EGC message received with conflicting Urgency and Distress priorities may NOT be printed out automatically, which could cause a delay in reacting to the vital information.
Read also: Empowering Global Communication with INMARSAT Satellites in shipping
If an EGC message is submitted with Urgency priority, service code C1 = 2 and another message is sent with Distress priority afterwards, priority code C1 = 3, the message with Urgency priority will be aborted and the message with Distress priority will be handled first.
Improper use of C2 service codes
There are cases when MSI providers submit an EGC SafetyNET message using improper C2 service codes and a sample is given below:
LES xxx – MSG 5213 – Met/NavWarn Urgent Call to Area: 35N 23E 300 – PosOK
FROM: Maritime Rescue Coordination Centre xxx
TO: ALL SHIPS IN xxxxxxx
SAR SITREP No: 02
FISHING BOAT ‘xxx’ WITH THREE PERSONS ON BOARD DEPARTED FROM xxx ISLAND ON xxx AT NOONTIME AND SINCE THEN NO INFORMATION ABOUT HER. PARTICULARS … SHIPS SAILING IN VICINITY ARE KINDLY REQUESTED TO KEEP A SHARP LOOK OUT
INFORMING MRCC
REGARDS
DUTY OFFICER
The message was sent using service code C2 = 24 “Met/Nav warning to circular area“, as shown in the message header, but the text of the message content is concerned with SAR co-ordination. The correct C2 code for this type of message should have been C2 = 14. Use of the incorrect C2 codes, may delay delivery of the vital SAR information.
Another example is the improper use of rectangular addressing, e. g., service code C2 = 04, for coastal warnings whereby the addressed rectangular area covers areas far beyond coastal areas. In this case, ships receive unwanted information for areas other than those in which they are navigating.
Reception of EGC SafetyNET Coastal Warnings is an option and to receive these messages, MESs should be programmed or set up accordingly; otherwise Coastal warnings will not be received, regardless of the ship’s position. If a coastal warning-type message is addressed to a rectangular area, ALL ships, whose position is inside the addressed rectangle, will receive the message. The main problem here is not only misusing service codes, which are specified by the Understanding Inmarsat SafetyNET: A Vital Tool for Maritime SafetyInternational SafetyNET Manual, but reception (and printing) of multiple unwanted messages which ships may never require.
Improper use of C4 repetition codes
Repetition codes detailed in Understanding Inmarsat SafetyNET: A Vital Tool for Maritime Safety“Repetition codes (C4)”, are used by MSI providers to “instruct” the Inmarsat-C system to repeat a SafetyNET message a finite number of times or at specific intervals until cancelled by the information provider.
MSI is submitted for broadcast with repetitions, either 6 minutes after initial broadcast (with 6 minutes “echo”) or every 1, 2, 3, 4, … 48, … or 120 hours until cancelled by the MSI provider. Each message, when submitted for broadcast, is given a unique reference number. When the message is received by the MES, the reference number is “recorded” by the mobile terminal and stored in the memory. When the same message is re-broadcast later, using any C4 repetition codes, MESs receive it and “recognize” the reference number by cross-checking the list of numbers of messages already received. Messages received with the same unique reference number will not be displayed or printed out for a second time.
Note: An EGC message, which requires a multiple broadcast, should be addressed with the proper repetition code and requires only a single submission to the LES. The process of repeated broadcast will be controlled by the repetition code.
When the same SafetyNET message is submitted for broadcast for a second (or third or more) time, the addressed LES will give the message another reference or sequence number and mobile terminals will not be able to “recognize” it as the same message. In this case each subsequent message submitted to the LES for repetition will be received by MESs and may be automatically printed out.
SafetyNET monitoring shows that some MSI providers do not use the recommended repetition code and in this case MESs receive and print unwanted messages, which will fill up the MES‘s memory rather quickly and waste printing paper.
Notes:
- Some MSI is broadcast only once on receipt using repetition code C4 = 01.
- Mariners are advised not to engage in routine communications during the periods designated for scheduled MSI SafetyNET broadcasts. The 6 minute repeat or echo should be used for non-scheduled broadcasts.
Below is an example of the same weather forecast submitted for broadcast twice and having two different reference numbers:
LES xxx – MSG 1032 – MetWarn/Fore Safety Call to Area: xx – PosOK
xxx CSAT 23423440010402 xx-NOV-2010 09:55:41 103000
SECURITE
HIGH SEAS BULLETIN FOR METAREA xx ISSUED AT 0800 ON xx NOV 2010 BY THE MET OFFICE …
LES xxx – MSG 1033 – MetWarn/Fore Safety Call to Area: xx – PosOK
xxx CSAT 23423440010402 xx-NOV-2010 10:10:13 103453
SECURITE
HIGH SEAS BULLETIN FOR METAREA xx ISSUED AT 0800 ON xx NOV 2010 BY THE MET OFFICE
The message (size about 4 800 characters) was received and printed twice since it was submitted to the LES for broadcast twice and was given two separate reference numbers – 103000 and 103453.