§ 81.183

Prevention of interference.

(a) Before any signals or communications are transmitted on any frequency, the licensed operator attending a land station or a land mobile station subject to this part (or the person responsible in lieu of a licensed operator in respect to land mobile stations for which the requirement of an operator license is waived by the Commission; or in a public coast station using telephony, the landline telephone operator under the supervision of the licensed operator) shall first listen on the associated receiving frequency, and when necessary on the land or mobile station transmitting frequency, to determine insofar as is practicable whether transmission by the land or mobile station will interfere with communication already in progress, whenever the involved frequency or frequencies are assigned to other stations within the same interference area (for example, all stations in the Great Lakes region are considered, with respect to operation on frequencies below 30 Mc/s, to be in the same interference area): Provided, That the requirement may be waived by the Commission upon appliIcation therefor in behalf of individual land stations which employ other effective means to avoid interference.

(b) Whenever a radiocommunication in the maritime mobile service is already in progress between two mobile stations or between a mobile station and a coast station and it appears to be interfered with by a subsequent transmission from another mobile station, the latter must cease transmitting at the first request of either of the other two, except as priority may be otherwise determined by § 81.181. The station requesting this cessation must indicate the approximate length of the wait imposed upon the mobile station whose transmission is suspended.

(c) Communications between ship stations, between ship and aircraft stations, or between land stations and land mobile stations subject to this part, must not interfere with the work of coast stations. When this work is thus interfered with, the ship, aircraft, land mobile, or land station which causes such interference must stop transmitting or change to a different authorized frequency upon the first request of the coast station concerned: Provided, That this requirement shall not apply to ship or aircraft stations when they are trans

mitting signals or communications relating to a ship or aircraft in distress.

(d) Coast stations when operating on a frequency below 3500 kilocycles or above 30 Mc/s shall not carry on, or attempt to carry on, communication with any station which, under the currently prevailing conditions of transmission or reception, is not within reliable communication range of the coast station: Provided, That this provision shall not apply in event of distress, either actual or impending.

§ 81.184 Transmission of traffic lists by coast stations.

(a) Public coast stations are authorized to transmit, on their normal working frequencies in the appropriate bands, lists of official call signs (or, alternatively in the use of telephony, the names of the respective ships), in alphabetical order so far as practicable, of all mobile stations for which they have traffic on hand. These traffic lists shall be transmitted at intervals of at least two hours and not more than four hours during the working hours of the coast station. The use of calling frequencies for this purpose is prohibited; however, coast stations may announce on a calling frequency that they are about to transmit such call lists on a specified working frequency.

(b) In operating pursuant to paragraph (a) of this section, public coast stations shall be governed by the applicable provisions of the International Radio Regulations.

NOTE: See paragraphs 1067 and 1300 of the International Radio Regulations, Geneva,

1959.

§ 81.185

Transmission to plurality of mobile stations.

Information for the general benefit of mariners (including storm warnings and ordinary weather and hydrographic information) and press material may be transmitted by a coast station simultaneously to a plurality of mobile stations in the maritime mobile service: Provided, That the times at which such transmissions (except storm warnings and urgency and safety messages) are scheduled to begin, the maximum duration of each such transmission, and the specific radio-channels and class of emission used therefor, shall, with respect to each coast station, be subject to approval by the Commission.

§ 81.186 Hours of service of stations on land.

(a) Each coast station or marineutility station on shore whose hours of service are not continuous shall not suspend operation before having concluded all communication required in connection with a distress call or distress traffic.

(b) Each public coast station whose hours of service are not continuous shall not suspend operation before having concluded all communication (in addition to that designated in paragraph (a) of this section), within the scope of its normal operations, involving messages or calls originating in or destined to mobile stations or marine fixed stations which are within normal range of the coast station and which, in the case of mobile stations, have signalled their presence before the effective suspension of operation of the coast station.

(c) Unless otherwise authorized by the Commission upon adequate showing of need therefor, each class I public coast station shall maintain continuous hours of service during the entire period of validity of the station license.

(d) Unless otherwise specified by the Commission for particular stations, the hours of service of each class II and class III public coast station shall, within the scope of its normal operations, be such as to adequately meet the requirements of the particular region served by the station.

(e) Unless otherwise specified by the Commission for particular stations, the hours of service of limited coast stations and marine-utility stations on shore shall be determined by the station licensee in accordance with the requirements of the respective ships served by each station.

(f) The Commission, as public interest, convenience, or necessity requires, may order, at any time, the licensee of a public coast station not authorized for continuous hours of service to increase the hours of service of such station as may, in the discretion of the Commission, be required to provide adequate public service: Provided, That such requirement shall not be prescribed without the consent of the station licensee unless, after hearing, the Commission shall determine that such requirement will promote public convenience or interest or will serve public necessity, or

the provisions of the Communications Act will be more fully complied with.

(g) Unless otherwise specified by the Commission for particular stations, the hours of service of stations subject to this part which are not operating in the maritime mobile service shall be determined by the station licensee in accordance with the requirements of the service carried on by the station(s) involved, subject to such applicable conditions and limitations as are imposed by the rules of the Commission or by the International Radio Regulations.

§ 81.187

Procedure relative to distress communication.

(a) Applicable regulations. In addition to the governing provisions of the Radio Regulations, Geneva, 1959 (see Article 36 thereof) applicable to the transmission and interception of distress signals and the handling of distress traffic, land stations which are subject to this part shall, in cases of distress, be governed by the following paragraphs of this section. No provision of the International Radio Regulations shall prevent the use by a land station, in exceptional circumstances, of any means by telecommunication available to it for the purpose of assisting a mobile station in distress. A land station receiving a distress message shall, without delay, take the necessary action to advise the appropriate authorities responsible for providing for the operation of rescue facilities.

(b) Acknowledgment of distress message. Stations of the maritime mobile service which receive a distress message from a mobile station which is, beyond any possible doubt, in their vicinity, shall immediately acknowledge receipt. However, if it appears that the mobile station in distress is not in their vicinity, a short interval of time shall be allowed to elapse before acknowledging receipt of the message, in order to permit stations nearer to the mobile station in distress to acknowledge receipt without interference. All stations which hear a distress call shall immediately cease any transmission capable of interfering with the distress traffic and shall continue to listen on the frequency used for the emission of the distress call.

(1)

(c) Form of acknowledgment. The acknowledgment of receipt of a distress message is transmitted, when radiotelegraphy is used, in the following form:

(i) The call sign of the station sending the distress message, sent three times; (ii) The word DE;

(iii) The call sign of the station acknowledging receipt, sent three times; (iv) The group RRR;

(v) The distress signal SOS.

(2) The acknowledgment of receipt of a distress message is transmitted, when radiotelephony is used, in the following

form:

(i) The call sign or other identification of the station sending the distress message, spoken three times;

(ii) The words THIS IS;

(iii) The call sign or other identification of the station acknowledging receipt, spoken three times:

(iv) The word RECEIVED;

(v) The distress signal MAYDAY.

(d) Control of distress traffic. (1) The control of distress traffic is the responsibility of the mobile station in distress or of the station which, in accordance with the governing provisions of the International Radio Regulations, has transmitted the distress message. These stations may, however, delegate the control of the distress traffic to another station.

(2) The station in distress or the station in control of distress traffic may impose silence either on all stations of the mobile service in the area or on any station which interferes with the distress traffic. It shall address these instructions "to all stations" or to one station only, according to circumstances. either case, it shall use:

In

(i) In radiotelegraphy, the abbreviation QRT followed by the distress signal SOS. The use of the signal QRT SOS shall be reserved for the mobile station in distress and for the station controlling distress traffic;

(ii) In radiotelephony, the signal SEELONCE MAYDAY. The use of this signal shall be reserved for the mobile station in distress and for the station controlling distress traffic.

(3) If it is believed to be essential, any station of the mobile service near the ship, aircraft, or other vehicle in dis

tress, may also impose silence. It shall use for this purpose:

(i) In radiotelegraphy, the abbreviation QRT followed by the word DISTRESS and its own call sign;

(ii) In radiotelephony, the word SEELONCE followed by the word DISTRESS and its own call sign or other identification.

(4) Any station which has been notifled to cease transmission in connection with a situation of distress shall not resume transmission on any frequency which may cause interference to distress signals or traffic until notified by the station in control of the distress traffic that the distress traffic has ceased and transmission may be resumed, or until notified by the station issuing the original notice that transmission from the station in question will not interfere with the distress signals or traffic.

(e) Transmission of a distress message by a station not itself in distress. (1) A land station which learns that a mobile station is in distress shall transmit a distress message in any of the following cases:

(i) When the station in distress is not itself in a position to transmit the distress message;

(ii) When the person responsible for the land station considers that further help is necessary;

(iii) When, although not in a position to render assistance, it has heard a distress message which has not been acknowledged. At the same time, all necessary steps shall be taken to notify the authorities who may be able to render assistance.

(2) The transmission of a distress message under the conditions prescribed in subparagraph (1) of this paragraph shall be made on either or both of the international distress frequencies (500 kc/s radiotelegraph; 2182 kc/s radiotelephone) or on any other available frequency on which attention might be attracted.

(3) The transmission of the distress message under the conditions prescribed in subparagraph (1) of this paragraph shall always be preceded by the call indicated hereunder, which shall itself be preceded whenever possible by the radiotelegraph or radiotelephone alarm signal. (See § 81.188.) This call consists of:

(c) The call sign of the transmitting station, sent three times.

(ii) When radiotelephony is used: (a) The signal MAYDAY RELAY, spoken three times;

(b) The words THIS IS;

(c) The call sign or other identification of the transmitting station, spoken three times.

(4) When the radiotelegraph alarm signal is used an interval of 2 minutes shall be allowed, whenever this is considered necessary, before the transmission of the call mentioned in subparagraph (3) (i) of this paragraph.

§ 81.188 Radiotelegraph and radiotelephone alarm signals.

(a) The international radiotelegraph alarm signal consists of a series of twelve dashes sent in one minute, the duration of each dash being four seconds and the duration of the interval between consecutive dashes one second. The purpose of this special signal is the actuation of automatic devices giving the alarm to attract the attention of the operator when there is no listening watch on the distress frequency.

(b) The international radiotelephone alarm signal consists of two substantially sinusoidal audio frequency tones transmitted alternately. One tone shall have a frequency of 2200 cycles per second and the other a frequency of 1300 cycles per second, the duration of each tone being 250 milliseconds. When generated by automatic means, the radiotelephone alarm signal shall be transmitted continuously for a period of at least 30 seconds, but not exceeding one minute; when generated by other means, the signal shall be transmitted as continuously as practicable over a period of approximately one minute. The purpose of this special signal is to attract the attention of the person on watch or to actuate automatic devices giving the alarm.

(1) That a distress call or message is about to follow; or

(2) The transmission of an urgent cyclone warning. In this case the alarm signal may only be used by coast stations authorized by the Commission to do so; or

(3) The loss of a person or persons overboard. In this case the alarm signal may only be used when the assistance of other ships is required and cannot be satisfactorily obtained by the use of the urgency signal only, but the alarm signal shall not be repeated by other stations. The message shall be preceded by the urgency signal.

(b) In cases described in subparagraphs (2) and (3) of paragraph (a) of this section, the transmission of the warning or message by radiotelegraphy shall not begin until two minutes after the end of the radiotelegraph alarm signal.

§ 81.190 Radiotelegraph watch by coast

stations.

(a) All coast stations (public and limited) licensed to use telegraphy on frequencies within the band 405–535 kc/s shall, during their hours of service, take the necessary measures to insure an efficient safety watch by a duly licensed radiotelegraph operator on the international distress frequency 500 kc/s for three minutes twice each hour, beginning at x h. 15 and x h. 45 Greenwich mean time. The safety watch maintained shall be efficient for classes A1, A2, and A2H emissions. For this purpose, either headphones or loudspeaker may be used, on condition that use of the loudspeaker is not less effective than use of headphones. While maintaining this watch, the operator shall not use or operate any radio equipment (such as, for examples, broadcast receivers, or amateur transmitters or receivers) not actually required in connection with maritime mobile service.

(b) All public coast stations licensed to use frequencies in the authorized bands between 405 and 535 kc/s shall, during their hours of service, remain on watch on the calling frequency 500 kc/s, except when the operator is transmitting on 500 kc/s, operating the station transmitting or receiving equipment on any other frequency authorized for transmission or reception in the maritime

mobile service (including maintenance of the watch on 143 kc/s if required as provided by paragraph (c) of this section) if it is not possible to maintain at the same time, by any practicable means, the watch for calls on 500 kc/s. Any practicable means of maintaining this watch would include a loudspeaker or headphones energized, if necessary, by an additional radio receiver (other than the receiver actually in use for nonwatch purposes) which is tuned to 500 kc/s. The provisions of this section, however, shall not relieve the coast station from complying with the requirements for a safety watch as prescribed in paragraph (a) of this section.

(c) On condition that compliance with the following requirement shall in no way interrupt or reduce the efficiency of the safety watch prescribed in paragraph (a) of this section, each coast station equipped and licensed for communication by means of class A1 emission on frequencies within the band 90-160 kc/s shall, during its hours of service when not engaged in communication with another station of the maritime mobile service, keep watch for calls every hour on the frequency 143 kc/s for five minutes beginning at x h. 35 Greenwich mean time.

[28 F.R. 13983, Dec. 21, 1963, as amended at 34 F.R. 1545, Jan. 31, 1969]

(a) Each public coast station licensed to use telephony shall, during its hours of service, keep watch on the frequency (s) authorized for working, which are used normally by mobile stations for transmission by telephony to the particular coast station; or in lieu of such watch, the coast station shall, during its hours of service, monitor such frequency (s) by any apparatus which will automatically intercept signals from mobile stations with no less efficiency than that attainable by a watch and which automatically indicates the interception of such signals by either aural or visual

means.

(b) As an alternative to keeping watch on (or monitoring) a working frequency in the band 1605-3500 kc/s as prescribed by paragraph (a) of this section, a public coast station may, in

the discretion of the station licensee, keep watch on 2182 kc/s.

(c) (1) Each public coast station licensed to transmit by telephony on one or more frequencies within the band 1605 to 3500 kc/s shall, during its hours of service for telephony, maintain an efficient watch for reception of A31 and A3H 'emissions on the carrier frequency 2182 kc/s whenever such station is not being used for transmission on that frequency: Provided, That the Commission may exempt any coast station from compliance with this requirement if it considers that the frequency 2182 kc/s is adequately guarded by other stations or that circumstances relative to the operation or location of the involved coast station are such as to render this requirement unreasonable or unnecessary for the purpose of this paragraph. The watch referred to in this subparagraph will not be deemed "efficient" unless the coast station is capable of normally receiving A3 and A3H2 emissions on 2182 kc/s from mobile stations within the associated working frequency service area of the coast station, including periods of time when the coast station is transmitting on any other authorized frequency.

2

(2) Each public coast station licensed to transmit by telephony on one or more frequencies within the band 156-162 Mc/s shall, during its hours of service for telephony, maintain an efficient watch for the reception of Class F3 emission on the frequency 156.800 Mc/s whenever such station is not being used for transmission on that frequency: Provided, That the Commission may exempt any coast station from compliance with this requirement if it considers that circumstances relative to the operation or location of the involved coast station are such as to render this requirement unreasonable or unnecessary for the purpose of this paragraph.

1 The requirements of this paragraph are applicable as follows:

(a) To all transmitters type accepted after Mar. 1, 1969;

(b) To all transmitters first installed after Jan. 1, 1970; and

(c) To all transmitters after Jan. 1, 1974. 2 The watch maintained shall be for reception of emissions as follows: Until Jan. 1, 1977, emissions A3 and A3H; after Jan. 1, 1977, emission A3H.