(1) RADIO TRAFFIC

DISTRESS AND EMERGENCY RADIO TRAFFIC

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Radio regulations, concerning distress, emergency, and safety traffic, are contained in the International Telecommunication Convention of Madrid, 1932, which has been ratified by many of the maritime nations. This publication, with the International Radiotelegraph Convention of Washington, can be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C., at 30 cents. Pertinent extracts from the Madrid Convention are given in Hydrographic Office Publication No. 205, Radio Aids to Navigation. The following items merit special attention.

Distress wave. The wave of 500 kc (600 m) shall be the international distress wave. It shall be used for that purpose by ship stations and aircraft stations in requesting help from the maritime services. This wave must preferably be used in type A, and B. Vessels which cannot transmit on the international distress wave shall use their normal calling wave.

Times of listening on distress wave.-In order to increase safety of life at sea (ships) and over the sea (aircraft), all stations which normally listen on the waves of the authorized bands between 365 and 515 kc (822 and 583 m) must, during their working hours, make the necessary provisions to insure the watch on the distress wave twice per hour, for 3 minutes beginning 15 minutes and 45 minutes after the hour, Greenwich mean time. During these intervals, transmissions must cease in the bands 460 to 550 kc (652 to 545 m) and transmission of type B waves are forbidden.

Distress and urgent signals.-The international radio distress signal SOS indicates that a ship, aircraft, or other mobile station sending it is threatened by serious and imminent danger and requests immediate assistance. Many cases occur when the degree of danger is such as not to warrant the use of the SOS signal but assistance is required. The international urgent signal XXX has been provided for those cases to indicate that the calling station has a very urgent message to transmit concerning the safty of a ship, aircraft, or other mobile station or concerning the safety of some person on board or sighted from on board. Shipmasters are urged to refrain from the use of the SOS signal when the XXX signal will serve the purpose.

Priority of distress call. The distress call shall have absolute priority over other transmissions. All stations hearing it must immediately cease all transmission capable of interfering with the distress traffic and must listen on the wave used for the distress call.

Distress call and message. The distress call shall include the distress signal transmitted three times, the word DE and the call signal of the station in distress transmitted three times. The distress message shall follow as soon as possible; it shall include information regarding the position of the craft in distress, the nature of the distress, the nature of the help requested, and any further information which might facilitate assistance.

The distress call shall, as a general rule, be immediately preceded by the alarm signal. See below.

Repetition of distress call.-Any station which is not in a position to render assistance but which has heard a distress message for which acknowledgement of receipt has not immediately been given, must take all possible steps to attract the attention of stations which are in a position to furnish help.

In the United States, special instructions request that, if during distress traffic, it is evident that coastal radio stations are unaware of the disaster, some ship which is not taking an active part in the distress traffic, shall relay the distress message to the nearest Government or commercial shore station in order that the proper officials may be notified, that additional aid may be sent out from the coast, and that preparations may be made to receive survivors. In sending this message the greatest care must be taken not to interfere with the distress traffic; whenever possible the message should be sent on other than the distress wave.

Control of distress traffic. The control of distress traffic shall devolve upon the station in distress or upon the station which for special reasons has sent the distress call. These stations may delegate the control of the distress traffic to another station.

Silence during distress traffic.-Any station which becomes aware of distress traffic must listen to this traffic even if it does not take a part in it. For the entire duration of distress traffic it shall be prohibited for all stations which are aware of this traffic and which are not taking part in it, either to use the distress wave of 500 kc (600 m) or the wave on which the distress traffic is taking place or to use type B waves.

Distress-signal interference. The successful expedition of distress traffic requires the adherence of all the operators to the rules of procedure and noninterference. One of the most conspicuous difficulties in handling this traffic is the interference caused by the operator, who, no doubt, is anxious to assist, but by his efforts in trying to persuade another operator to maintain silence, is himself contributing to the confusion. It sometimes happens that several operators are trying to silence an operator that they feel is an offender while they themselves are offenders.

If one vessel is sending, when a distress signal is broadcast, it is easier to copy through her interference than add further interference by several vessels trying to stop her.

See page 25 for procedure to be followed to avoid distress-signal interference. End of distress traffic.-A vessel having sent a distress call has started an extensive machinery of rescue, which not only extends to shipping within range but to Government agencies, and perhaps to the suspension of other traffic. So the responsibility devolves on such a ship to keep her position and condition known. Should her trouble become remedied, the fact should be immediately broadcast that radio traffic may be cleared and shipping proceed. Urgent signal.-The urgent signal shall consist of the group XXX transmitted three times, with the letters or each group, as well as the consecutive groups well separated. The urgent signal shall have priority over all other communications except distress communications and all stations hearing it must take care not to interfere with the transmission of the message which follows the urgent signal. Stations hearing the urgent signal must listen for at least 3 minutes.

Alarm Signal.—The alarm signal shall consist of a series of 12 dashes sent in 1 minute, the duration of each dash being 4 seconds and the duration of the interval between dashes, 1 second. It may be transmitted by hand or by means of an automatic instrument. The only purpose of this special signal is to set automatic alarm apparatus into operation. It must only be used to announce that a distress call or message is to follow, or to announce the transmission of an urgent cyclone warning; in the latter case it can only be used by coast stations duly authorized by their government.

Safety signal. The safety signal shall consist of the group TTT, transmitted three times, with the letters of each group, as well as the consecutive groups, well separated. This signal shall be followed by the word DE and three transmissions of the call signal of the station sending it. It announces that this station is about to transmit a message concerning the safety of navigation or giving important meteorological warnings.

REQUESTS FOR ASSISTANCE FROM VESSELS IN DISTRESS

Radio-equipped vessels in distress and requiring assistance should make use of the distress signal SOS or the urgent signal XXX as described on page 23. Services of the Coast Guard can be secured by using the radio call NCU "Any Coast Guard Unit" or by sending a message to any shore station addressed to Coast Guard. Shore radio stations will forward to the Coast Guard all information regarding vessels requiring assistance unless such information is contained in a message specifically addressed elsewhere.

Similarly a vessel sighting another vessel in distress may send the distress signal SOS or make a report of the facts by use of the urgent signal XXX, or the radio call NCU "Any Coast Guard Unit," or by calling direct any commercial or Government radio station which is capable of transmitting on 500 ke (600 m).

Such requests for assistance should be transmitted on the international distress wave 500 kc (600 m). See page 23. Small craft

(1) VESSELS IN DISTRESS

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can request assistance from the Coast Guard by using the frequency 2,670 as noted on page 26.

Any or all radio stations will forward such requests for assistance to the appropriate assisting agencies.

Information desired in requests for assistance.-If the following information is included in the original request for assistance, it will place the responsible Coast Guard officer in a position to determine immediately the types and number of vessels required to render adequate aid, thus greatly facilitating the work of the Coast Guard and avoiding any unnecessary delay in the dispatch of assistance. 1. Name, type, and nationality of vessel.

2. Position, course, and speed (including drift).

3. Nature of trouble and condition of vessel, sea, and wind.

4. Number of persons on board.

5. State whether or not Coast Guard assistance is required.

Recommended procedure for securing assistance and avoiding distress traffic interference. As a result of conferences on distress traffic communications, the United States Coast Guard has adopted a recommended course of action, based on International Radio Regulations and established practice, to be taken by radio-equipped vessels in order to get assistance as quickly as possible. This recommended procedure is as follows:

When in distress.-Transmit your distress message on the international distress wave (see p. 23), giving all information which will leave no doubt as to your trouble and position. Approximately 10 minutes after the transmission of the original distress message, the ship in distress is requested to transmit slowly on the distress wave, "MO" and its own call signal for 3 minutes. This will enable ships and radio direction-finder stations in the vicinity to take radio bearings and to plot accurately the position of the distressed ship, thereby permitting assistance to be dispatched without difficulty and delay. When another is in distress:

1. Give absolute priority to distress call and messages relating thereto. 2. Cease all transmissions capable of interfering with the conduct of distress communications.

3. Maintain absolute silence if within range and not actually taking part in the conduct of distress communications.

4. Concentrate attention on the distress case and intercept all information possible.

5. If unquestionably in vicinity of distressed vessel, acknowledge receipt of the distress message, if received, giving your position to the vessel in distress, stating action being taken.

6. Be extremely careful not to interfere with stations more favorably situated to handle the case.

7. Do not try to silence other units, i. e. “QRT”, unless you are in control. The vessel in distress controls: Permit him to handle the situation without being interferred with. The vessel in distress may delegate this control to some other station more favorably situated. Do not interfere with the station lawfully controlling the situation.

In Minor Cases of distress or other trouble.-Use the urgent signal XXX, or the general call for any Coast Guard Unit NCU.

United States Coast Guard Form 800-D is a card form covering the above recommended procedure. It is designed to be posted on the bridge and in the radio room of radio-equipped vessels; copies of this card can be obtained upon request from the Commandant, United States Coast Guard, Washington, D. C.

Small commercial and private craft, equipped with radio, may obtain the assistance of the Coast Guard by transmitting the distress message on the frequency 2,670 kc (112 m). The Coast Guard stands continuous watch on 2,670 kc (112 m) and will answer emergency calls made thereon. This distress frequency is employed, in addition to the 500 kc (600 m), because a suitable antenna is more easily accommodated on small craft than the relatively long aerial required for efficient operation at the lower frequency.

Small craft and airplanes, not equipped with radio, may obtain the assistance of the Coast Guard off the coast of Florida and along the Gulf coast by following the procedure given on page 20.

RADIOTELEGRAPHIC WEATHER BROADCASTS

Forecasts and general weather information are broadcast daily by the United States Weather Bureau from a number of Government and commercial radio stations for the benefit of marine, aviation, and commercial interests. Storm and hurricane warnings are broadcast whenever issued.

Storm warnings and notices concerning the safety of navigation at sea of an urgent nature are broadcast by United States naval radio stations (those whose call sign commence with N) immediately upon receipt and repeated hourly thereafter for a period of 12 hours or until superseded. Similar broadcasts are made by Ensenada, P. R. (via WPR).

Complete details relative to this service are published in circulars issued by the Weather Bureau, which, together with a card descriptive of storm warnings, may be obtained upon application to any United States Weather Bureau office. Details are also given in Hydrographic Office Publication No. 205, Radio Aids to Navigation. These publications give the schedules with times and frequencies of all broadcasts, together with tables for decoding as needed.

The General broadcast schedules are:

Washington, D. C. (via NAA and NSS).-A major marine bulletin, issued twice daily by the United States Weather Bureau, contains forecasts, warnings, atmospheric pressure distribution, and surface weather observations for the regions of the Atlantic Ocean, Gulf of Mexico, and the Caribbean Sea, suitable for preparing weather maps at sea. This bulletin is rebroadcast by San Juan (via NAU). Base charts for the preparation of weather maps at sea will be supplied free by the United States Weather Bureau to masters of vessels who regularly take and forward weather observations to the Bureau or to the Hydrographic Office, United States Navy.

In addition to the above, the Arlington station (NAA) also broadcasts twice daily a North American Continental Weather Report (Angot Bulletin). This bulletin begins with the words "Angot Paris" and is in the new International Code.

It contains surface observations for the United States, Canada, the Atlantic Ocean, the Gulf of Mexico, and the Caribbean Sea.

San Juan, P. R. (via NAU).-A weather bulletin is broadcast daily during the period July 1 to November 15, inclusive, containing weather reports from stations in the West Indies, followed by weather forecasts, storm warnings, and a synopsis of atmospheric

pressure distribution. Hurricane warnings and advisory messages are broadcast whenever issued. The Washington Major Marine Bulletin is rebroadcast by this station.

Guantanamo Bay, Cuba, (via NAW).—The San Juan bulletin is rebroadcast from this station and hurricane warnings and advisory messages are broadcast whenever issued.

Local weather forecasts and information are broadcast from numerous stations along the Atlantic and Gulf coasts and about the Caribbean Sea. Stations making such broadcasts, together with full advice regarding the same, are listed in the Hydrographic Office Publication No. 205, Radio Aids to Navigation, and other publications noted under Radio References on page 21.

Tropical Storms.-During the hurricane season, June 1 to November 30, ships in the Gulf of Mexico, Caribbean Sea, and Southern North Atlantic Ocean are urged to cooperate with the United States Weather Bureau in order that more complete information may be supplied to ships and for the purpose of warning the inhabitants of coastal areas.

Reports should be sent when a storm is encountered or when the presence or formation of one is suspected. The nearer the ship is to the center of the storm, the more valuable is the radio weather report. It is realized that in such a situation the master and his officers are occupied with the duties of navigating the ship, but the dispatch of an observation by radio under those weather conditions may result in timely advices to other ships at sea and in warnings to the inhabitants of islands and coastal communities where life and property are in jeopardy.

These reports should be sent in the New International Code, form 5, preceded by the ship's name, but unsigned. Messages should be checked collect, and when in the Atlantic Ocean north of latitude 35° N., the observations should be addressed "Observer, Washington"; in the Gulf of Mexico, Caribbean Sea, and the Atlantic Ocean south of latitude 35° N., they should be addressed "Observer, Jacksonville." If a copy of the International Meteorological Code is not on shipboard it will be found in Hydrographic Office Publication No. 205, Radio Aids to Navigation, or a copy may be obtained on application to the United States Weather Bureau, Washington, D. C. If code is impracticable, the message may be sent in plain language, giving the ship's position, Greenwich time of observation, direction and force of the wind, state of the weather, and barometer reading. Weather reports should not be sent when weather conditions are normal, except by ships with which specific arrangements have been made by the United States Weather Bureau.

RADIOBEACONS AND DISTANCE FINDING

The United States Lighthouse Service operates a system of radio beacons, established along the United States coasts. This system has recently been coordinated with that of the Lighthouse Administration of Canada in order that the methods of operating the radiobeacon system of the United States and Canada might become more effective. In order to facilitate the widest utilization of this system of navigational aids, there are issued at intervals radiobeacon charts,

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