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:
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.1 the power-operated sliding watertight door
closure alarm power sources may be those used to close the doors;
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.2 the fire-extinguishing pre-discharge alarm
power source may be the medium itself; and
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.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).