Aircraft Cabin Management

The light fantastic: The continuing evolution of cabin LED lighting technologies

Lighting

LED lighting technologies continue to evolve, generating more power with increased efficiency. But the real advances are perhaps in how they are used, as Paul Eden finds out.

This piece first appeared in the May/June issue of Aircraft Cabin Management, you can read the full magazine  

A decade or more ago, the industry was excited by the dawning era of LED cabin lighting. Compared to conventional solutions, LED technologies were smaller and lighter, more energy efficient, required less maintenance and, through digital control, promised to make lighting effects integral to the passenger experience.

Expectations were high, but have they been met? Niels Dose, product sales & key account manager of base maintenance services at Lufthansa Technik, believes it’s a resounding “yes”. “With regards to maintenance, we see that exchange rates on most LED-based lighting systems are reduced compared to traditional systems,” he notes.

In today’s difficult market, Dose observes an inevitable slow-down in lighting upgrades and retrofits, but counters the trend with a positive note. “The general benefits of LED technology over conventional lighting have been recognised for a while and we strongly believe that cabin lighting is, and remains, a major element in offering passengers a whole new inflight experience. Hence, it will continue to play a major role on the retrofit market.”

Matt Opisso, director of business development and strategy at Collins Aerospace, is a cabin lighting specialist. He says the company has done extensive analysis comparing traditional fluorescent lightning with LED, identifying the need to replace fluorescent elements at least twice yearly, while LED systems typically perform well for five years or more before anything other than limited maintenance is required. Opisso speaks of ‘first-generation’ LEDs and the latest developments, noting that while many airlines continue to retrofit from fluorescent to LED, others are replacing older LED systems. 

“We’re seeing LEDs today that are at least ten times brighter,” he explains. “They are used everywhere – in TVs and cars, for example – and they are becoming lighter, significantly smaller and more efficient. We’re aligning our aerospace lighting with that development.”

In terms of lighting effects, Opisso references emerging technologies and features. “The colour rendering index [which quantifies the ability of a light source to render an object’s colour accurately] is 99+ [out of 100], and we’re seeing particular interest in circadian lighting features, enabled through the technology and efficiency of LEDs.”

The new generation of LEDs is also enabling novel applications beyond necessary lighting and ambience. Opisso describes “panelised lighting”, where a wall, monument or display includes an embedded micro-LED panel. “We already have the Secant panel in our product line; it can be used like a TV, showing custom content for branding or advertising.” He also sees possible future applications where Secant replaces traditional ordinance and other cabin signage.

Reading the right way

While no doubt appreciating the latest IFE offerings, there remain passengers for whom hours spent in an airline seat are perfect for settling down with a traditional book. It’s a delight historically spoiled by reading lights barely fit for purpose. But LED technology is delivering important change here, too.

Opisso explains that Collins Aerospace has applied its micro-LED technology to the humble reading light. “We use a single light fitting containing an array of LEDs. It’s software-driven, and replaces at least three traditional reading lights, with considerably more functionality, including the ability to display a seat number or logo.”

Glass and optics specialist Schott reduced its cabin lighting portfolio in 2020, but continues in the market with a sharper focus on detail and reading lights. Vice-president at Schott Aviation Philip Fischer reports: “All the promise of LEDs came true and is still coming true. Now we’re using the latest generation of LEDs. We just updated our portfolio of seat lighting and our latest innovations include the Jade reading light, which is touch-operated.”

Passengers direct Jade using their fingertips, its beam tracking their movements to rest at the ideal position. “You feel like a Jedi,” Fischer jokes. “You touch the light and the beam follows your fingers. We’ve combined the technology with fibre optics to narrow the beam down to exactly where it’s wanted. We worked with [UK design agency] PriestmanGoode on the design, which brings something remarkable to the passenger experience. The light even follows as you move in your seat so that it continues to shine exactly where you want it.

“We also have an LED strip for accent and mood lighting. It’s bendable to match curved contours, while our RGBW LED package enables any atmosphere to be created through colour mixing.” Fischer says colour is an essential component in creating cabin ambience, but also notes that new-generation LEDs enable a more individual approach for business and first class passengers to customise their space.

Combining fibre optics with LEDs also provides new colour options. Modern, brighter LEDs are particularly suited for use as light sources for fibre optics. “These solutions have been on the market for maybe five to seven years,” Fischer notes, “but more powerful LEDs are increasing the efficiency of colour mixing and creating possibilities for new product development.” 

Yet fibre optics are essentially light-carrying cables and ought to be completely opaque, carrying light from the source to the point at which is needed. So how do Schott and others create continuously illuminated strips? “That’s part of our core technology,” Fischer reveals, without saying very much more.

Optimising the ambience

LED technology has enabled passenger experience at a fundamental level, helping optimise the cabin ambience for boarding, mealtimes, sleep and waking, for example. Now, improved flexibility and controllability is driving a more scientific approach to helping passengers emerge from the flying experience feeling better than ever. “Human-centric lighting, examining the effect of lighting on health, is enabling airlines to influence passenger behaviour and health,” Fischer explains. 

Based in Hamburg. Germany, Jetlite is all about human-centric lighting, as CEO and co-founder Dr Achim Leder elaborates. “We work with the cabin LED system; we can use any RGBW source. Our software integrates into the user’s cabin management system. We worked with Lufthansa Technik to produce a solution within its product, for example. Our scientifically proven solution uses the chrono-biological impact of light to positively affect the body’s internal clock, not only when moving between time zones but also for passengers on early morning flights.”

 Illustrating the latter, he suggests that a passenger catching an imaginary 06:00 hours flight from London to Paris must wake up at 03:30 to reach the airport in time. If they normally rise at 07:00, their internal clock is already behind by 3.5 hours when they board the plane. This so-called ‘social jet lag’ affects people even when they travel in the same time zone.

‘Scientifically proven’ is an easy phrase to use without necessarily having the data to back it up, but Leder’s background includes more than six years’ research into light effects on the body clock, including early laboratory trials. Working alongside Diehl Aviation, Airbus and Osram, he progressed the effort into a widebody cabin mock-up, before moving on to a series of eight test flights with Lufthansa.

Flown between Boston and Munich, the airborne trials covered a six-hour time difference in a seven-hour flight. Leder explains: “We developed a range of lighting scenarios based on the data we collected. Since then, we’ve done lot of work, mostly with Airbus, but also with Boeing, and MROs, including Lufthansa Technik and Airbus Upgrade Services, to optimise the process of bringing the system into the cabin.” 

Right now, the entirety of the Lufthansa A350 and 747-8 fleets are equipped with Jetlite, along with Air Vistara’s Dreamliners and another European carrier will be announced soon. Interestingly, Leder says regular business travellers commented on their improved feeling of wellbeing after experiencing Lufthansa’s Jetlite-equipped A350 service, without knowing the system was in use.

Its control system manipulates the existing LED lighting to minimise the effects of traditional and social jet lag. In the economy cabin it acts universally but, Leder says, “For business and first class we have individualised lighting solutions. We have a client bringing a new first-class product to market in 2022, for example, and along with Recaro we have developed a business class system with personalised lighting in the seat shell.”

He suggests a future option where economy class passengers may be able to book seat positions within the cabin according to their lighting ‘times’, adding an interesting new possibility for enhancing the passenger experience. 

For the time being, individual control of anything more than the reading light in economy is impractical and could easily result in a ‘Christmas tree cabin’, but Leder does see scope for a degree of customisation where airlines have seat dividers installed for a post-Covid era.

Finishing touches

Dirk-Achim Schevardo, Diehl Aviation’s senior manager of business development for cabin systems, observes that lighting a cabin effectively ultimately relies on more than LEDs and control systems. 

“The combination of light and cabin lining creates the appearance. If light can’t escape from the space envelope where the lighting fixtures are integrated, then an otherwise perfect lining will be spoiled. Alternatively, if everywhere is the same brightness, with no shadows, it’s difficult for people to orientate themselves.”

Lighting

Aircraft cabin illumination is usually by indirect, reflected light, which means surface finishes, material choices and design are important. Diehl therefore employs A350 and Boeing 787 cabin mock-ups to help define its product line, enabling its engineers, designers and customers to optimise lighting designs in a true-to-life setting.

Compared to fluorescent lighting, Schevardo notes that an LED fit for an A321 is typically 20 per cent lighter and consumes one third less power, but he is most excited about how the latest technologies are transforming cabin appearance. 

“Look at the new Airbus Airspace cabin,” he enthuses. “It has the kind of technology where we can illuminate flat surfaces, thereby emphasising patterns and showing special, customised designs. We also use flexible light strips that generate ‘wow’ effects and ambience. And all the time, LEDs are becoming more efficient, generating even less heat than before, using less power and lasting longer.”

Nonetheless, he insists: “We aren’t selling electronics, we’re selling aircraft cabin appearance. The point isn’t simply to supply a lighting system capable of creating millions of colours, it’s to create a cabin that satisfies customers. We understand light, appearance and how people react to light, and the ability for airlines to create an optimised cabin ambience at the push of a button is what we sell.”

A decade or so ago, LEDs were achieving wider acceptance in the cabin. Today, they continue to evolve technologically and in their application. As Opisso over at Collins Aerospace concludes: “Combining cabin lighting with digital displays and customised scenes is like merging the commercial market of TVs, phones and other technologies in the aircraft cabin – it’s pretty exciting.” 

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