| � |
| � |
 |
IAMSAR Manual
|
 |
� |
| � |
|
Communications
2.17 Maritime Radio Telex
|
2.17.1 Telex messages may be sent via satellite or terrestrial radio. Radio telex is sometimes called Radio Teletype (RTT) or Narrow-Band Direct Printing (NBDP).
2.17.2 RCCs and RSCs may use radio telex for shore-to-ship distress traffic. Such services should be established and indicated in the ITU List of Coast Stations.
2.17.3 Each station having radio telex capabilities is assigned a selective call number in addition to its regular station identity, but MMSI numbers may also be used for radio telex. Selective call numbers for coast stations are four digits, and are listed in the ITU List of Coast Stations; selective call numbers for vessels (which normally need to send radiotelex via a coast station, due to the equipment required) are listed in the ITU List of Ship Stations and have five digits.
2.17.4 NAVTEX is used to promulgate navigation and meteorological warnings and other safety-related information to vessels and may be used by SAR personnel for SAR-related broadcasts.
2.17.5 The World Wide Navigational Warning System (WWNWS) is for long-range NAVAREA warnings and coastal NAVTEX warnings. It provides for globally co-ordinated transmissions by giving NAVAREA Co- ordinator duties to a State for each of 16 NAVAREAs as shown in Figure 2-1.
2.17.6 While all WWNWS broadcasts must be in English, additional broadcasts may be made in a second language.
2.17.7 The types of warnings which SAR personnel may send over WWNWS include distress alerts and information about overdue or missing aircraft or vessels. Collectively, these types of alerts, combined with navigation and mete6rologlcal warnings, are called maritime safety information (MSI). |
| � |
|
|
2.18.1 Inmarsat also can and should be used to broadcast MSI. Every RCC should make arrangements with an associated NA V AREA Co-ordinator or other authority recognised by Inmarsat to make such broadcasts on its behalf over Inmarsat's SafetyNET system. SafetyNET provides an automatic, global method of broadcasting SAR messages to vessels in both fixed and variable geographic areas. SafetyNET broadcasts can be received by vessels equipped either with SafetyNET receivers or Inmarsat-C SESs configured to perform EGC receiver functions.
2.18.2 A SafetyNET Users Manual shou1d be obtained from Inmarsat. This Manual prescribes procedures and exact coding which must be followed for preparing SafetyNET broadcasts, including SAR broadcasts.
2.18.3 It is appropriate and advisable to promulgate distress alerts over both NAVTEX and SafetyNET. All SOLAS ships and many fishing and other vessels sailing within NA VTEX coverage areas can be expected to carry 518 kHz NAVTEX receivers. However, some may carry equipment to receive MSI over SafetyNET in addition to NA VTEX.
2.18.4 Normally, the most practical way to handle SAR broadcasts over SafetyNET is to send them to all vessels within a desired radius of a specified position.
2.18.5 Using an all-ships broadcast to identify a vessel to divert for SAR operations requires time to obtain responses from available vessels, and to select an appropriate one for the task, and may affect quite a few vessels. As a first step it may be prudent to determine whether an appropriate ship can be identified via AMVER or another ship reporting system, and contacted. Other factors should be considered, such as the high cost of ship diversions, the likelihood of the alert being false, and the potential proliferation of distress and urgency traffic which sounds bridge alarms. SafetyNET is a reliable, economical and important SAR tool, but it must be used wisely. |
| � |
|
|
2.19.1 Radio telegraph (WT) is a Morse Code service provided for distress and safetY on the frequencies 500 kHz and 8364 kHz. The basic Morse signals are displayed in Appendix A.
2.19.2 WT has been a core part of the maritime mobile service since the early 20th century, and will continue to be voluntarily used into the next century; however, after 1 February 1999, SOLAS vessels are not required to continue use of the service. A key value of this service is that it overcomes Ianguage barriers, but it depends upon trained radio operators.
2.19.3 WT transmissions other than distress calls are supposed to be kept to one minute or less.
2.19.4 During their hours of service, ships are supposed to watch on 500 kHz for three minutes twice per hour, beginning at h+15 and h+45, by an operator using headphones or a loudspeaker. During these periods, only distress signals are permitted. The last 12 seconds of each period may be used to announce urgent or safety broadcasts. |
| � |
2.20 Phonetic Alphabet and Figure Code |
| 2.20.1 An example of phonetic alphabet and figure code which may be used when speaking or spelling out call signs, names, search area designations, abbreviations, etc., Is found in the International Code of Signals. There are other versions of the phonetic alphabet which may be used just as effectively. |
| � |
2.21 Spoken Emergency Signals and Procedural Words |
| 2.21.1 There are three spoken emergency signals used by aircraft and vessels: |
(a) Distress signal: MAYDAY (pronounced M'AIDER) is used to indicate that a mobile craft is in distress and requires immediate assistance, and has priority over all other communications for example, when a vessel has a person overboard messages are sent.
(b) Urgency signal: PAN-PAN (pronounced PAHN-PAHN) is used when the safety of a mobile craft is in jeopardy or an unsafe situation exists that may eventually involve a need for assistance, and has priority over all but distress traffic.
(c) Safety -signal: SECURITY (pronounced SECURITAY) is used for messages concerning safety of navigation or giving important meteorological warnings.
|
2.21.2 Any message beginning with one of these signals has precedence over routine messages. The signal is repeated three times at the beginning of the message. The hearer should listen, not transmit during these messages, and assist if possible.
2.21.3 An aircraft commander or vessel captain experiencing a distress situation should declare a distress condition using the MAYDAY signal. However, if these words are not used, and there is any doubt about whether an emergency exists, the hearer should assume it is an actual or potential emergency and obtain enough information to handle the emergency intelligently.
2.21.4 Basic spoken radio procedural words which SAR personnel should understand and use are found in Appendix A. |
| � |
2.22 On-scene Communications |
| 2.22.1 Besides equipping SAR aircraft to communicate on the frequencies 2182 kHz, 3023 kHz, 4125 kHz, 5680 kHz, 121.5 MHz, and 123.1 MHz, some SAR authorities have provided for other communication equipment on-scene, such as: |
- SART -compatible 9 GHz radars for SAR facilities;
- disposable droppable radios operating on 123.1 MHz VHF/ AM which can be dropped for survivors to use in communicating with SAR aircraft or SAR vessels on-scene; and
- radio installation aboard SRUs which will actuate radiotelephone alarms aboard vessels in the vicinity to help establish communications with them more directly.
|
| 2.22.2 The means of communication between SAR facilities and the RCC or RSC depends upon local plans and arrangements, and on whether the RCC or RSC is communicating directly or via an alerting post. |
| � |
2.23 Electronic Positioning |
2.23.1 While information is often received about the position of a distressed craft when the SAR system is alerted, many alerts are received without positions or with inaccurate ones. Positioning is the determination of the general location or co-ordinates of the scene of the distress/while direction finding or homing is used to help pinpoint the position.
2.23.2 Distress position data are crucial to SAR personnel. Vessels and aircraft use various navigation equipment to determine their own positions, and sometimes this equipment is connected to or integrated with communications equipment to include positions in alert messages automatically. Electronic positioning means include radio beacons used in conjunction with radar, Decca, Loran A, and Loran C.
2.23.3 Bearings from shore can be obtained by shore facilities within range of radio or other electronic signals compatible with DF equipment. Two or more bearings plotted as lines of position (LDPs) can fix the position of an aircraft or vessel by triangulation. Some maritime SAR authorities operate DF services to obtain bearings to Channel 16 transmissions; DF equipment can be effectively used whether it is fixed on land or installed aboard SAR facilities.
2.23.4 There are also a variety of satellite systems used for positioning. These systems, Global Navigation Satellite Systems (GNSS), e.g., GLONASS and the Global Positioning System (GPS), are based on a constellation of satellites. They are available for a wide variety of three-dimensional position fixes for military and civilian uses world-wide. Three-dimensional capability and accuracy to within 10 metres makes it attractive for aeronautical applications. However, many GNSS-equipped devices are capable of determining positions only to within 100 metre accuracy.
2.23.5 Having a very precise GNSS search target position is valuable, but does not alleviate the need for homing capabilities, especially if the SAR facility is not also GNSS-equipped, or if operations take place at night or in other low-visibility conditions. |
| � |
| � |
| � |
| � |
|
|
� |
