4 General
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - Code on Alerts and Indicators, 2009 - 4 General

4 General

  4.1 The presentation of alerts and indicators should be clear, distinctive, unambiguous and consistent.

  4.2 All required alerts should be indicated by both audible and visual means, except the emergency alarms of 3.2 which should be indicated primarily by a signal. In machinery spaces with high ambient noise levels, signals should be supplemented by indicators, presented in accordance with 6.1. Signals and announcements may also be supplemented by indicators in accommodation spaces.

  4.3 Where audible alerts are interrupted by public announcements the visual alert should not be affected.

  4.4 A new alert condition should be clearly distinguishable from those existing and acknowledged, e.g., existing and acknowledged alarms and warnings are indicated by a constant light and new (unacknowledged) alarms and warnings are indicated by a flashing light and an audible signal. Audible signals should be stopped when silenced or acknowledged. At control positions or other suitable positions as required, alert systems should clearly distinguish between no alert (normal condition), alert, silenced and acknowledged alert conditions.

  4.5 Alerts should be maintained until they are acknowledged and the visual indications of individual alerts should remain until the fault has been corrected. If an alert has been acknowledged and a second fault occurs before the first is rectified, the audible signal and visual indication should be repeated.

  4.6 Alerts and acknowledged alerts should be capable of being reset only in case the abnormal condition is rectified.

  4.7 The presentation and handling of alarms, warnings and cautions indicated on the navigation bridge should comply with the requirements of module C of resolution MSC.252(83) where applicable to ships with Integrated Navigation Systems (INS) and, where fitted, with the requirements of a bridge alert management system.

  4.8 Required alert systems should be continuously powered and should have an automatic change-over to a stand-by power supply in case of loss of normal power supply. Emergency alarms and 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 pre-discharge 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.

  4.9 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 changeover to the emergency source of electrical power in case of loss of normal power supply.

  4.10 Failure of power supply of required alert and alarm systems should be indicated by an audible and visual alarm or warning.

  4.11 Required alert and alarm systems should, as far as is practicable, be designed on the fail-to-safety principle, e.g., a detection circuit fault should cause an audible and visual alarm; see also FSS Code, chapter 9, paragraph 2.5.1.5.

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

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

  4.14 Software and data for computerized alert and alarm 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 software and data.

  4.15 Cables for fire and general emergency alarms and public address systems and their power sources should be of a fire-resistant type where they pass through high fire risk areas, and in addition for passenger ships, main vertical fire zones, other than those which they serve. Systems that are self monitoring, fail-safe or duplicated with cable runs as widely separated as is practicable may be exempted provided that their functionality can be maintained. 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.

  4.16 To the extent considered practicable by the Administration, general emergency alarm, fire alarm and fire-extinguishing pre-discharge alarm should be arranged so that the audible signals can be heard regardless of failure of any one circuit or component.

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

  4.18 The number of alerts and indicators which are not required to be presented on the navigation bridge should be minimized.

  4.19 The system should be designed so that alerts can be acknowledged and silenced at the authorized control position. All alerts presented on the navigation bridge should be capable of being acknowledged and silenced as required in module C of resolution MSC.252(83) where applicable to ships with Integrated Navigation Systems (INS) and, where fitted, with the requirements of a bridge alert management system.

  4.20 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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