This resulted in a hazardous condition for crewmembers escaping to safety. Although requirements exist to provide illuminated exit signs on all doors along egress routes in the interior of the ship, in the casualties noted, the loss of electrical power resulted in no illuminated visual escape markings during the crisis. The PL material emits light that becomes visible if the light source is turned off. Without the light source to re-energize it, the PL material gives off the stored energy for a period of time with diminishing luminance. The purpose of placing signs on the bulkhead, within 6 to 23 inches of the deck is to ensure continued visibility even during heavy fire and smoke conditions.
Smoke collects in the overhead and obscures sings placed at eye level.
The bottom edge of EXIT signs and arrows are to be located on the adjoining bulkhead no lower than 6 inches above the deck or higher than 23 inches. Where more than one sign is required in the same location, the top of the highest sign is to be no higher than 30 inches above the deck. In compartments having dual egress routes through the space, both routes are to be marked. Ordering information for Emergency Egress Markers can be found in the Shipboard Safety Equipment Shopping Guide. Department Heads shall ensure through instruction and drill that all crewmembers of his department are familiar with all escape routes from their work spaces and living areas.