Aircraft LED lighting technologies hold out the promise of significant improvements in cabin lighting systems. These improvements include more reliable and robust aircraft lighting systems, greater flexibility in installation and a much wider range of lighting effects. These benefits can lead to direct improvements in safety and in day to day benefits, as well as significant improvements in cabin ambience. Yet LED lighting also offers significant benefits in terms of ease of installation, maintenance and operating costs.

LED Lighting already holds a significant position in terms of general passenger Health and Safety and in ergonomic issues e.g. management of passengers by flight crew, and in the emergency evacuation of passengers. This is where lighting safety functionality currently stops. Yet LED Lighting systems offer far more than mere cosmetic improvements in cabin ambience, colour schemes or small improvements in lighting functionality.

LED Lighting Systems are likely to become one of the most robust systems onboard, surviving throughout the lifetime of the airframe with minimal maintenance and even surviving the destruction of the aircraft itself. This is perhaps an overly dramatic statement, but nevertheless the fact is that we can engineer LED Lighting to continue normal operation even in the most adverse circumstances.

Compare that to the fragility of existing lighting systems. We assume these systems will fail - even when relatively minor mishaps occur to the aircraft such as heavy landings. Indeed, we expect to evacuate the aircraft in the dark, precisely because of our conventional experiences with current lighting systems. We expect aircraft power to fail, the fluorescent tubes to be destroyed and the wiring to become an impediment to escape. Then we shrug our shoulders as if to say "what do you expect"?

Yet we should expect more. Far more. We can significantly improve general health and safety with more ergonomically useful lighting systems, and we can also improve safety when things go drastically wrong.

Most discussion on LED lighting begins with comparisons between the obvious characteristics of LED's and incandescent or fluorescent lighting as they are supplied today. LEDs are small and their use is currently confined to 'spot beams', rather than say lighting the interior of a cabin. Yet this is more a limitation in the way LEDs are deployed than a limitation in LEDs themselves. LEDs are supplied as spot beams because these are easy to manufacture and represent an obvious niche in the market (the sun is a rather significant 'spot beam' too!). LEDS appear relatively expensive compared to fluorescent tubes, but this is again because the true costs and benefits are rarely laid side by side (and is related to market volume and demand).

The fact is, we expect to see fluorescent tubes because they are a part of everyday life at home, in the Mall and onboard - and fluorescent tubes have served us very well indeed - we are comfortable with them. As a result, we accept their limitations, almost as a fact of life, even if these shortcomings are (in the cold light of day) not really so acceptable. In practice, it may be hard to shake the fluorescent 'habit'. LEDS, on the other hand, appear to be annoyingly bright spots of monochromatic light.

Yet our experience of fluorescent tubes isn't always happy and they do little to improve the ambience of the places we live, work in. For that we often prefer incandescent lighting, which provides more 'spread spectrum' lighting and a warmer feel to our colour schemes. However, incandescent lighting is not best suited for aircraft lighting, due to its general inefficiency and high heat output. It is probably about time their use in aircraft was completely reviewed.

There is no doubt that LEDs are creating a lot of excitement with all the possibilities on offer. LED lighting is a fast moving area, with new LED technologies appearing almost daily. The range of colours, light output, efficiency and many other characteristics - improving almost on a par with the frequency of Pentium and graphic card upgrades in our PCs. Therein, of course, lies the rub. We are waiting to see what pops up next over the horizon. Thus LEDs appears to be a technology in flux.

Yet this is missing the point. LEDs are here today and we should be planning to install the systems that will allow us to gain benefits that are available now and those we know will be available in the very near future. We should invest in the infrastructure of our aircraft in such a way that it becomes economic to upgrade should we wish to design and change colour schemes, corporate colours (e.g. on transfer of ownership) or functionality and use (e.g. changes in cabin class configurations).

This is probably especially true for leased aircraft, where quite dramatic changes can be made quickly and without physically changing so many cabin fixtures, and for airlines operating large fleets that may wish to improve aircraft utilisation, rather than dedicating specific aircraft to specific routes.

LEDS are indeed useful for spot beam applications, where light can be focussed directly where it is needed, in a range of colours and without disturbance to other passengers, in a word - control. But this is only the beginning, and LEDs are quite capable of providing much, much more.

LEDS can provide colour wash to surfaces, creating sophisticated ambient and indirect lighting effects. It can do this by employing a range of colour LEDs singly or in combination or by employing tunable colour LEDs. This can be done with great precision, providing sophisticated control over colour, tone and brightness to generate an infinite variety of mood, brand or corporate effects.

The only limit is in our imagination. This is not just fanciful stuff, but is genuinely productive and useful. To see this, it is only necessary to compare the functional benefits of LED lighting systems to the alternatives:

The "Lows":

• Low Heat
• Low Failure rates
• Low Maintenance
• Low Weight
• Low Power
• Low Radio Output
• Easy Installation, Anywhere!

The "Highs":

• High Efficiency
• Long Life
• Flexibility
• Control
• Reliability
• Robustness
• Redundancy
• Battery backup
• Safety

LEDs are vibration, switching and temperature tolerant with extremely rapid response times. LED lighting can be installed in places currently unserved (i.e. virtually anywhere) and without the nightmare of wiring and power that currently accompanies existing lighting systems (difficulties with installation and reliability of existing lighting systems has resulted in compromises - even in emergency lighting - that should be eliminated).

It is possible to control LED lighting in a way not possible with fluorescent lighting and to do this in a redundant, fault tolerant way that drastically improves reliability, significantly reducing the risk of an aircraft 'going tech' and increasing the intervals between essential maintenance, as well as generally reducing maintenance effort.

LEDs do not generate radio interference, as does fluorescent lighting.

Positive lighting and directional guidance can be provided in emergencies.

The low power requirements of LEDs, also means that it is possible to continue to light the cabin even when aircraft power has failed (how many times have you sat in an aircraft when the lights failed due to a flight deck mishap with the APU?). The ability to continue to provide full cabin lighting in an emergency may be the single most important application yet.

Subtle and sophisticated lighting effects delivered with power and control - this is the promise of LED lighting. Programmable effects simulating the changes in the day from morning through to evening, and mood lighting matched with the in-flight service, providing subtle passenger prompts easing both crew tasks and passenger management as well as providing a more fulfilling experience for all.

Many atmospheric and zoning effects can be created which can be tried out using 3D modelling and simulation and then programmed into the aircraft with complete safety and reliability.

Essential to the successful long-term implementation of the full range of possibilities offered by LED lighting, is the need to address key issues:

• Modular Design, with agreed control and communication protocols.
• Flexibility and adaptability in electronic systems design.
• 'Plug and Play' upgradability.

LEDs means significant long-term change for aircraft cabin lighting - and with a potential shift to s/w development. Existing suppliers will resist change, basing their position on market dominance. More enlightened manufacturers will develop strategies to migrate to the new technology without undermining existing products and markets. This does not mean that fluorescent tubes are dead, as there will be a significant retrofit and support market, purely due to the long life of our aircraft. Hence, aircraft will continue to be delivered with existing lighting technologies for some time.

Rather than dramatic change, we should expect the market to be "LED" by the regional and corporate jet manufacturers (as is so often the case with new technology), to incorporate LED lighting in their new aircraft deliveries - perhaps piecemeal at first in spot, accent and safety lighting (as is already happening), until momentum gathers pace. Enlightened airlines (pun intended) undergoing fleet replacements, Lessors or those intending to strengthen their brands will specify new high performance lighting systems that can only be delivered by LEDs. They will do this without expecting a price hike - for there is no need for one. Rather, the economics of LEDs should light the way for many other much-needed improvements, perhaps the most significant of which is safety.

We should all certainly try our hardest to provide environments in our aircraft that encourage positive feelings in our passengers and so help make the whole experience of flying more comfortable and edifying - especially in these difficult times. LEDs offer one of the most straightforward and powerful ways to change the look and feel of aircraft cabins - literally in an instant. We should also remember that all of us as human beings devote 90% of our attention to what enters our eyes - and make the most of this simple fact.