Transport category aircraft are required by 14 CFR 25.812 to have emergency lighting systems,including floor proximity marking systems.Typical floor proximity marking systems installed on transport category aircraft have been primarily comprised of incandescent luminaries spaced at intervals on the floor, or mounted on the seat assemblies,along the aisle.The requirement for electricity to power these systems has made them vulnerable to a variety of problems,including battery and wiring failures,burned-out light bulbs, and physical disruption caused by vibration,passenger traffic,galley cart strikes,and hull breakage in accidents.

Attempts to overcome these problems have led to the proposal that non-electric photo- luminescent materials be used in the construction of floor proximity marking systems.To assess the viability of this proposal, performance demonstrations of systems made with such materials were conducted. It was found that strontium aluminate photoluminescent marking systems can be effective in providing the guidance for egress that floor proximity marking systems are intended to achieve; in contrast, zinc sulfide materials were found to be ineffective.

Strontium aluminate is a newer photo- luminescent material that was not investigated during the initial search for marking system technologies.It is somewhat slower to charge than zinc sulfide,but after a short initial discharge interval in which the zinc sulfide is slightly superior,the light output level of
strontium aluminate is greater and more sustained.

This increased light output suggests that marking systems made of strontium aluminate might also make effective aircraft floor proximity escape path marking systems, especially where aircraft operations allow longer system charging times.

As a consequence of these developments, manufacturers of photoluminescent materials have approached the FAA and its international regulatory partners to allow the use of these materials in the manufacture of floor proximity escape path marking systems.demonstrated in the CAM1 Aircraft Cabin Evacuation Facility (ACEF).