3 General
Clasification Society 2023 - Version 9.38
Statutory Documents - IMO Publications and Documents - International Codes - Alarms and Indicators - Code on Alarms and Indicators, 1995 Resolution A.830(19) - 3 General

3 General

  3.1 The presentation of alarms and indicators should be clear, unambiguous, and consistent.

  3.2 All required alarms should be indicated by both audible and visual means, except the emergency alarms of 2.2 which should be indicated primarily by audible alarms. In machinery spaces with high ambient noise levels, audible alarms should be supplemented by visual alarms in accordance with 5.1. Audible alarms may also be supplemented by visual alarms in accommodation spaces.

  3.3 A new alarm condition should be clearly distinguishable from those existing and accepted, e.g., existing and accepted alarms are indicated by a constant light and new alarms are indicated by a flashing light. At control positions or other suitable positions as required, alarm systems should clearly distinguish between normal, alarm, and accepted alarm conditions.

  3.4 Alarms should be maintained until they are accepted and the visual indications of individual alarms should remain until the fault has been corrected, when the alarm system should automatically reset to the normal operating condition. If an alarm has been accepted and a second fault occurs before the first is rectified, the audible and visual alarms are to operate again.

  3.5 Alarms should only be capable of being cancelled if the condition causing them has been dealt with successfully.

  3.6 Required alarm systems should be continuously powered and should have automatic change-over to a stand-by power supply in case of loss of normal power supply. Emergency alarms and primary alarms should be powered from the main source of electrical power and from the emergency sources of electrical power defined by SOLAS regulations II-1/42 or II-1/43 unless other arrangements are permitted by those regulations, as applicable, except that:

  • .1 the power-operated sliding watertight door closure alarm power sources may be those used to close the doors;

  • .2 the fire-extinguishing medium alarm power source may be the medium itself; and

  • .3 continuously charged, dedicated accumulator batteries of an arrangement, location and endurance equivalent to that of the emergency source of electrical power may be used instead of the emergency source.

  3.7 Required rudder angle indicators and power-operated sliding watertight door position indicators should be powered from the main source of electrical power and should have an automatic change-over to the emergency source of electrical power in case of loss of normal power supply.

  3.8 Failure of the normal power supply of required alarm systems should be indicated by an audible and visual alarm.

  3.9 Required alarm systems should, as far as is practicable, be designed on the fail-to-safety principle, e.g., an open detection circuit should cause an audible and visual alarm; see also SOLAS regulations II-2/13.1.2 and II-1/51.1.4.

  3.10 Provision should be made for functionally testing required alarms and indicators. The Administration should ensure, e.g., by training and drills, that the crew is familiar with all emergency and primary alarms.

  3.11 Required alarms and indicator systems should be functionally independent of control systems and equipment, or should achieve equivalent redundancy. Any additional requirements for particular alarms in the IMO instruments applicable to the ship should be complied with.

  3.12 Computer programs for computerized alarm and indicator systems should not be permanently lost or altered as a result of power supply loss or fluctuation. Provision should be made to prevent unintentional or unauthorized alteration of computer programs.

  3.13 Cables for emergency alarms and their power sources should be of a fire-resistant type and be run as directly as is considered practicable by the Administration. Equipment and cables for emergency alarms and indicators (e.g. watertight doors' position indicators) should be arranged to minimize risk of total loss of service due to localized fire, collision, flooding or similar damage.

  3.14 To the extent considered practicable by the Administration, emergency alarms should be arranged so that the audible alarm signal can be heard regardless of failure of any one circuit or component.

  3.15 Means should be provided to prevent normal operating conditions from causing false alarms, e.g., provision of time delays because of normal transients.

  3.16 Alarms and indicators on the navigating bridge are to be minimized. Alarms and indicators which are not required alarms and indicators for the navigating bridge should not be placed on the navigating bridge, unless permitted by the Administration.

  3.17 The system should be arranged so that all alarm signals can be accepted or cancelled at the appropriate control position only.

  3.18 In order to facilitate maintenance and reduce risk of fire or harm to personnel, consideration should be given to providing means of isolation of sensors fitted to tanks and piping systems for flammable fluids or fluids at high temperature or pressure (e.g. valves, cocks, pockets for temperature sensors).


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