5.4.2 Visual Alarms
5.4.2.1 Discrimination of Visual Alarms
Visual alarms should clearly differ from routine information on displays.
5.4.2.2 Presentation of Visual Alarms
Visual alarms should be flashing. The flashing display should change to steady display upon acknowledgement.
5.4.2.3 Presentation of Acknowledged Alarms
Acknowledged alarms should be presented by steady display.
5.4.2.4 Presentation of Normal Conditions (No Alarm)
Alarm indicators should be designed to show no light in normal conditions (no alarm) or should be nonexistent on displays.
5.4.2.5 Flash Rate
Flashing visual alarms should be illuminated for at least 50 % of the cycle and have a pulse frequency in the range of 0.5 Hz to 1.5 Hz.
5.4.2.6 Night Vision
Visual alarms on the navigating bridge should not interfere with night vision.
5.4.3 Audible Alarms
5.4.3.1 Use of Audible Alarms
Audible alarms should be used simultaneously to visual alarms.
5.4.3.2 Audible Alarms
Audible alarms should go off upon acknowledgment.
5.4.3.3 Focusing on Audible Alarms
Audible alarms should be differentiated from routine signals, such as bells, buzzers, and normal operation noises.
5.4.3.4 Sound Characteristic
Under normal working conditions, the alarm signals should be heard properly inside the wheelhouse and outside in the bridge wings, their sound characteristics should not be inconvenient to the human ear.
5.4.3.4.1 Sound Pressure
Audible alarm sound pressure, one meter from the source should be at least 75 dB(A), and at least 10 dB(A), or preferable 20 dB(A), above ambient noise levels existing during normal operations. Audible alarm sound pressures in a space should not exceed 115 dB(A).
5.4.3.4.2 Sound Frequency
With the exception of bells, audible alarms should have a signal frequency between 200 Hz and 2500 Hz, with the preferable range between 500 Hz and 1500 Hz.
