Avionics Technology: Evolution or Revolution in the Cabin

A look at cabin management systems

Cabin management systems (CMS) have come a long way in the last few years. I still have vivid recollections of long nights in the hangar troubleshooting relay logic circuits trying to figure out why certain passenger lights wouldn't work or why the boss could not hear the VCR audio on the headset. Everything was two wire technology and testing was accomplished using a Volt Ohm Meter (VOM) or test lamp.

Many systems of today use digital technology and almost anything in the virtual world may become possible to replicate.

The term "cabin management" does not necessarily blanket all the capabilities that are achievable in aircraft of today. Most CMS do include lighting controls along with audio and video selections but the ways these functions are achieved can be revolutionary.

Back in the good old days it was easy to run a wire to a switch from a power source. When the switch was selected on, electrical current would flow to a lamp and if a ground was in place and electrical current flowed, the light would glow. Back then the best quality light would come from halogen lamps and of course accompanying the light would be an abundant amount of heat. It was not uncommon for a cabin accommodating nine or 10 people to require 15 amps of current in the cabin reading light circuit. This was supported by large diameter wires, heavy-duty switches, and lamps but the concept employed two wires; one for power and the other for electrical ground.

Now cabin lighting can be engineered to complement the interior furnishings. Light emitting diodes (LED) are constructed to operate at rather precise color temperatures emitting tailored glows to enhance the surroundings. Not to mention the fact that LEDs produce significantly less heat than their halogen counterpart and enjoy notably longer life spans while requiring significantly less current consumption.

The control of these lights is often accomplished through a digital network. Reading light switches along with other passenger service items are grouped in a removable switch panel which is electrically connected through a digital bus to some type of controller that when commanded will provide the desired current flow to the appropriate lamp. Even the old fluorescent tubes can be replaced by LED strips which can provide as much light without the frequent fluctuations and high voltage associated with this technology along with being much less susceptible to breakage associated with handling (or mishandling).

Relay controllers can include built-in diagnostic capability with indicators advising the state of the various internal and external circuitries. This almost eliminates the need for a test lamp as indicators are already in place to see if the remote switch is functional along with power into and out of the control box. Another valuable feature is the ability to access this diagnostic information without having to physically put your hands on the box. Technology may allow cabin monitors to serve as diagnostic displays and either laptop interrogation or password access can allow technicians to view first hand system operational status.

Audiovisual systems
Audiovisual systems are also supported by newer digital controls. In the age of iPods and other forms of electronic media access, having a CMS that is multifaceted can significantly enhance both passenger comfort and make the most of the office in the sky. Provisioning interface ports for laptop tie in gives the cabin occupants the ability to review and edit presentations while en route. Having this feature coupled to Internet access will enable the home office to have the capacity to interact with on board conferences so those chosen to participate in the mission will be armed with the most up-to-date information when they disembark at their destination.

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