Switching Aircraft Interior Systems to Fibre Optics

With more airline passengers demanding in-flight Wi-Fi, system designers need to find a smart solution for migrating on-board systems to fibre optics. Here Thomas Heller is account manager, aerospace and defence, Molex, surveys the current state and major trends for aircraft OEMs.
One of the hottest technology trends relating to cabin electronics in civil aircraft is creating designs that accommodate all the passengers that now want to use their smartphones, tablets, and laptops on board. Passengers want, and will eventually demand, the ability to recharge their devices as well as gain Wi-Fi access to stream video, audio, and data files throughout the entire flight. Essentially, many flyers want aircraft to become flying Internet cafés.

This trend, of course, creates challenges when it comes to outfitting aircraft cabins with modern electronic and electrical solutions. Size, weight, available space, power, cost, and vibration — all of which come at a premium within aircraft system designs — must be considered.
To address the challenge, speeds and bandwidth over copper have increased dramatically over the last few years. But with copper, Wi-Fi access presents what amounts to an impossible obstacle, especially in cases where 300 passengers try to access Wi-Fi all at once.
In addition to ensuring there’s no interference from the wide variety of systems on plane airframe systems, there’s also the issue of sufficient bandwidth for that number of users, especially those accessing video and audio files. Aircraft on-board system designers are at the tipping point for switching to fibre optics.
Fibre vs. Copper
With device and connector manufacturers driving the push to make photon-to-electron conversion points as small and as light as possible, fibre optic interconnects generate interest for their ability to perform better than copper in the critical SWaP (size, weight, and power) areas. Size wise, fibre interconnects and cable assemblies can typically be smaller compared to copper-based products that have equal or less information through-put. As boxes become smaller in size with increased bandwidth, output requirements become a key design factor. It goes without saying that weight impacts directly on payload capacity and related fuel usage – so the lighter the better, and fibre optics provide greater bandwidth for transmitting information. This is particularly helpful when trying to maintain high-level signal integrity during the uploading/downloading of video and audio files.
One option in development is fibre optic flex planes. Flex planes, with fibres embedded in an engineering plastic sheet, can greatly reduce weight and cross-sectional area of a data system. The conformability helps manufacturing and the weight savings enhances fuel efficiency for the life of the aircraft. Whereas copper cables (with their higher weight) require quite heavy fixtures, ribbon fibre can be easily attached without additional mechanical fixtures.

Turning on to Light
Companies that provide cabling interconnects for printed circuit boards (PCBs) and PCB box units to in-flight entertainment system manufacturers are also designing new power supplies as well as wireless hardware and lighting systems. Some Aircraft manufacturers are also conducting flight simulation tests on fibre optic systems for future modifications and updates of cabin systems.
Another key area for design engineers to focus on in addition to the rapid growth in the number of fibre optic systems, the density of the PCBs will increase and the size of the boxes housing them will decrease. This has already occurred in laptops and other personal electronic devices, and the industry will soon see this within in-flight entertainment systems.
In the not-so-distant future, all phones in the backs of the seats will disappear while the big boxes under the seat, although growing smaller, will still contain seat power, hubs, and access points, along with more functionality. For on-board system designers to meet such needs, the use of fibre optic interconnects will become a mandatory requirement.