A lifejacket light is indicating light signal device usually attached to lifejacket or other PFD. During an emergency, it could uninterruptedly indicate the survivor’s location to increase the success rate of rescue. The most common lifejacket light is designed as automatic water-activated and flashing light type. But manual activation design and steady light are allowed by the regulation as well.

The forced regulation of lifejacket light is SOLAS MSC.81(70) for life-saving appliances (LSA). Other position-indicating lights such as lifebuoy light, life raft light and life boat light etc. are also covered by per standard. Besides the switch activation method and light type, another two basic features are working duration and light intensity. The MSC.81(70) has stipulated a lifejacket light should continue to provide a luminous intensity of not less than 0.75cd in all directions of the upper hemisphere for a period of at least 8 hours.


It appears the resolution MSC.81(70) was first adopted on 11 December 1998. Back then, the position-indicating locator lights are still adopted with the energy-wasting traditional light sources (such as incandescent bulb, halogen etc.) Entering in the 21st century, the lighting technology developing in a fast manner due to the massive appliance of LED technology. LED light source first adopted on marine life-saving lights in early of 21st century and become mainstream in the 2010s. Now days, almost every life-saving indicating lights are using LED, expect the partial Lifeboat position indicating light. With a single LED, even the worst lifejacket manufacturer could easily make their product work for more than 10hrs and exceed 0.75cd light intensity without any problem.

So, the question is are we still going to use a requirement 24years ago to speculate an essential lifesaving appliance? It is understandable the relevant agencies have many more priority subjects that need to work on. And several new MED directives regarding to position-indicating lights of LSA already have been carried out in 2019 and 2020. To request further tests for position-indicating lights based on EN60945 and ISO24408 standards. But I think it is time to improve the operating hours and luminous intensity requests as well. Because those are the key features in a dark-night sea accident. And there should be no dissenting opinions as most of the products are already produced at a higher level, the electronic and LED technology is also capable to do better.


What are the proper operating duration and luminous intensity we should propose for standard revision regarding to lifejacket light? Combine the mainstream products and rescue practice factors. Minimum 24h working time seems to be a more practicability number compare to existing 8h request.

As for luminous intensity, 0.75 candela is equivalent to 1 nautical mile visual distance. But remember that is an ideal experiment result. In reality, the weather and environmental factors should also take into consideration. However, there is a good reference which is the aviation survivor locator light, it was designed for aircraft emergency evacuation on the water. The relevant product standard for aviation life vest light is the Federal Aviation Administration TSO-C85b survivor locator light. It requires a minimum 1.0cd light intensity for the light.


In summary, the current standard requirement for lifejacket light with ”luminous intensity of not less than 0.75cd in all directions of the upper hemisphere for at least 8 hours.” Was a resolution adopted based on the circumstance of 20years ago and outdated technology. To improve the industry development and provide higher standard product consist with current technology. The proposal is revising the requirement to ”at least 24h working hours with a luminous intensity of not less than 1 cd”.


NOTE: Some of the content of this article may only represent the author`s personal opinions and for academic exchange purpose only.


By Johnny Zhang

April 20, 2022