Commercial aircraft passenger cabins have undergone a significant change over the past few decades in terms of features, functions and equipment. Airlines use passenger cabins as a representation of their brand image and gain patronage by providing competitive features, comforts and ambience
Aircraft cabin electronics include the monitoring & control of a large number of interconnected and electrically powered equipment and subsystems of the cabin. These include cabin illumination, air conditioning equipment, window shades, smoke detection and fire extinguishing systems, cabin overhead audio, water and waste systems, flight crew interface to various cabin functions and support for in-flight entertainment systems. Being a significant component of the overall cost of an aircraft, the airlines and the OEMs are looking to manage the cost of cabin electronics and service life of aircrafts.
In order to stay competitive, OEMs are adopting the latest technologies and investing in the evolution of next generation aircraft cabins. This requires a substantial amount of engineering services and the support from a large network of supplier organizations. This paper describes the transformations in the cabin features & functions and highlights key technologies being adopted.
Technology Brief and Trend
Cabin Applications: Cabin Illumination Control
Aircraft cabin illumination is the single most important piece of equipment that creates the ambience passengers look for during their journey. Cabin illumination comprises of ceiling wash lights, dome lights, seat lights, window lights and stairways. Today’s cabin illumination systems especially on long haul flights emphasize on ambience created by dazzling display of colors, hues, transitions and are aptly termed “mood lighting”. They not only create artificial night & day (known to reduce jet lag) but also influence passenger moods e.g. warm lights during dining. However, most low cost airlines operating on regional routes continue to prefer low cost installations that are plain white light with just a warm hue.
Cabin lighting has seen a revolution in the last few decades from incandescent lamps through fluorescent tubes to all-LED lights. LED lamps not only provide the cost advantage due to their long life, lower weight, low power consumption and ultra low switching times but can also be completely controlled electronically to obtain the right color and intensity to create any kind of lighting effect. Mood lighting sequences can be conveniently programmed using simple screen based selections that define the color, intensity and duration of each transition.
Cabin illumination can be a complex system to develop, install and maintain, yet very simple to operate. The flight crew is provided with a touch screen from where they can simply select any cabin zone to monitor and operate the lights. For a large aircraft, there can potentially be thousands of controllable lighting end points all along the length of the cabin and hence need a distributed hierarchical data network and controllers with digital addressing capability. The light intensity and color is controlled by PWM controllers that are embedded in the cabin panels and connected via data links to a central control system. Using digital control, it is possible to obtain an accurate color mix and intensity resolutions as per standards and specifications.
However, LED lights are very sensitive to ambient temperature and device current. They also have problems of degradation due to ageing, resulting in chromatic inconsistencies and color temperature shifts. Diagnostic monitoring, adaptive controls and predictive analysis can assist in managing these issues. Light color and intensity transitions should appear uniform across zones along the length of the cabin. This demands special considerations to manage time synchronization of the electronic components and adapt to data path latencies. LED lamps of different makes or from different manufacturing batches show variations in light output and have to be considered during implementation. Planning for correct placement of lamps in the cabin also demands a great deal of engineering expertise and tools, to create the right ambience and uniform illumination in all areas of the cabin.
In addition to new aircraft programs, there is a large market opportunity for cabin illumination upgrades in retrofit business offering various solutions - from fluorescent tube to LED replacements to complete refurbishments of the entire cabin lighting system.
Cabin Surveillance: Securing the Cabin
Post 9/11 terrorist attack, there has been a significant increase in security and surveillance initiative, especially in commercial aircrafts and airports. Cockpit door and passenger cabins are being equipped with cameras and the pilots and the cabin crew will be able to monitor all areas of the aircraft using display devices. The videos can also be transmitted to equipment outside the aircraft when the aircraft is on the ground, to analyze and archive the video footage.
Finger print recognition as a technology in the cockpit has also been considered to ensure that no one other than the pilot takes control of the aircraft. With face recognition and tracking systems maturing, continuous monitoring of the pilot position is possible to sound an alert if anyone else occupies the pilot seat during flight.
Highly sophisticated systems such as for tracking passenger movement, passenger authentication and identity protection are also being designed. However, it will need a higher level of systems maturity to implement such systems.