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Wednesday, April 1, 2015

Rotary, Pushbutton, Touchscreen: Switches Evolve with Next Generation Cockpits

Traditional rotary and lighted pushbutton cockpit switches are being reduced, but not eliminated as aircraft flight decks increasingly feature touchscreen display technology. In response to the growth in the number of displays used in cockpits, and the continuing evolution of the applications controlled by displays, switch manufacturers continue to expand the definition and importance of switches in the next generation flight environment.

by Woodrow Bellamy III

Cockpit switches will not be completely disappearing from flight decks any time soon, according to today’s leading aircraft Light-Emitting Diode (LED) pushbutton switch manufacturers. Avionics Magazine readers agree with the Aerospace Optics and Staco Systems of the world, with 60 percent of respondents to our “Cockpit Switches Survey” stating that their fixed- or rotary-wing aircraft currently require upgraded switch technology.

The need to upgrade stands despite new commercial and military air frames that have entered service in recent years. These feature Human-Machine Interface (HMI) designs centered around high definition displays that reduce pilot workload, increase automation and are highly adjustable based on the purpose of a flight mission or operation.

However, the new display-centered designs still feature switches for flight critical safety applications, such as controlling the landing gear and providing emergency electrical power. The results of our survey evidence this need, with findings that more than 50 percent of readers are interested in acquiring new switches for flight-critical applications, such as controlling the landing gear of an aircraft.

Just a Switch?

Currently, the most in-demand cockpit switches from operators, maintenance and installation centers as well as Original Equipment Manufacturers (OEM) for both forward fit and retrofit purposes are LED pushbutton switches, according to Craig Morgan, vice president of sales at Aerospace Optics, one of the largest aircraft switch manufacturers in the world.

“The trend is still bringing LED-lighted pushbuttons into the mainstream. LEDs had certain limitations that pigeon-holed them early on, but today the things we have been tackling with respect to advanced pushbuttons would be getting the LEDs to the point where they can be utilized by the OEMs in new aircraft clean sheet designs and productions,” Morgan told Avionics Magazine.

The Texas-based manufacturer, which also produces subassemblies and other systems, launched its new Nexus line of lighted push button switches this year, which have ARINC 429 to discrete conversation capability. This means it can transfer the control and exchange of information and commands between the aircraft’s analogue pushbutton control and digital bus interfaces.

“These are more than just lighted pushbutton switches, as the ARINC 429 to discrete signal converter capability allows them to communicate back to the ARINC or digital side of what’s happening on the aircraft,” says Morgan. “Nexus is a lighted pushbutton switch line with electronic function internal, which we’re calling ‘post processing’ and then, at the same time, we provide a way for that lighted pushbutton to communicate with an [Automatic Dependent Surveillance-Broadcast] ADS-B type system through an ARINC discrete converter.”

According to Morgan, the FAA’s NextGen air traffic modernization is “one of the real drivers for Aerospace Optics in the near future.” That is especially true for those switch manufacturers specified to the discrete dimming qualification levels for MIL-STD-202G and DO-160F temperature, thermal shock, and MIL-STD-704F aircraft power out standards.

Staco Systems is also bringing the traditional cockpit switch into the modern flight environment, along with illuminated panels, subsystems and data entry solutions. During Heli Expo 2015, Staco displayed its new illuminated panels, which use a polymer over acrylic paint to prevent light leakage, and its new S200 and S300 switches. The S200 was introduced with a focus on Size Weight and Power (SWAP), as the family of switches helps to reduce the size of the overall cockpit panel, says Bruce Gray, president of Staco Systems.

“The depth of the cockpit panel is normally determined by the length of a pushbutton switch because that will be the longest component in the panel, so you can’t make it any thinner than that push button switch, which is usually about 2 inches long plus all the wiring behind it,” says Gray. “Most of the switches on the market today are about 2 inches, maybe a little more. We introduced a four-pole switch right at 1 inch long, about half the length of the typical switch. That allowed the panels to be made thinner, so in effect the cockpit can be moved away from the pilot to give them a little more room.”

The Irvine, Calif.-based manufacturer also has focused on introducing solutions for space restricted helicopter cockpits where pilots have very specific application challenges, such as its keyboards used for navigation mappings systems by airborne law enforcement officers, and two-pole, 1-inch switches that are used for helicopter autopilot systems.

“We introduced a variant of that switch more for helicopter applications called a half switch. Instead of a normal square-face plate, it is almost like you took a normal switch and cut it in half,” says Gray. “The way we were able to do that was through the use of what we call the ‘optic stack’ of the switch, or the optics that are the core of a lighted push button switch. We have taken that optics technology and moved it over to our light plate product line. A switch mounts in a light plate. That’s the lighting you see inside a cockpit, the backlit panels.”

A Niche Market

Airbus A350 XWB flight deck overhead panel. Photo: Airbus.
Staco Systems and Aerospace Optics both agree and acknowledge that the overall space for switches in aircraft cockpits is getting smaller and smaller, but neither see the demand or need for lighted pushbutton switches completely disappearing any time soon. While the latest commercial airframe to enter into service — the Airbus A350 XWB — features six large interchangeable Liquid Crystal Display (LCD) screens, there are still a high number of applications controlled by switches in the cockpit. The above-head controls, for example, are divided into 13 different panels with more than 100 traditional flip or lighted pushbutton switches controlling the cabin pressure, engines, oxygen, and evacuation functions among other safety related applications.

“There could be an assumption that this technology niche is a dying breed, with so many cockpits using the multifunctional displays and even some suppliers and system integrators working on voice recognition technology. But it’s quite the contrary, it’s just that this is a very niche market place right now,” says Morgan. “There are times when operator interface demands a tactical response, you reach out and get a good response on a lighted push button as opposed to laying your finger on touchscreen or glass. So that market is holding very strong for us.”

As an example, Morgan mentions that the Boeing 787, a relatively new aircraft, is using Aerospace Optics’ switches in its cockpit for some of the critical safety applications, such as the smoke detection switch. He also mentioned the avionics completion and modification for both rotary and fixed wing as another major market for the company. “Much of that is driven by the FAA mandates that are always looming and some of the technology boost such as how every aircraft that now wants Wi-Fi connectivity,” he adds.

Morgan says outside of the cockpit Aerospace Optics is also still seeing high demand for its switches in cabin applications. That demand matches the results of the editorial survey, which found that more than 50 percent of Avionics Magazine readers are looking to acquire new switch solutions for both cockpit and cabin applications.

However, Mid Continent Instruments Director of Sales Tom Genovese echoed the thoughts of Staco Systems and Aerospace Optics, stating that the number of overall switches will continue to be reduced in next generation cockpits but certain functions will remain hardwired.

“It seems like the only knobs or buttons that you still see are the landing gear and the flap settings. I’ve seen some very clean designs of cockpits and it looks like the industry is going over toward the touch screens more — fully integrated touchscreen cockpits,” says Genovese. “I think the future will probably eliminate the switching and things like that in the cockpit, while still keeping some traditional switches in there to control flight critical safety functions.”

While Thales’ 2020 full integrated all touch screen display package shows what the cockpit prototype of the future will look like, at least for now, the switches are here to stay.

“As integrated cockpits embrace digital databus interfaces to major aircraft systems, we see greater demand for low profile pushbutton switches with integral sunlight readable indicators/annunciators that have the look and feel of traditional switches,” Jim Kramer, president of Astronics - Luminescent Systems told Avionics Magazine.

Gray says that Staco has also seen more popularity for the use of switch reducing touchscreen display technology in the U.S., but that the glass displays did not have the same popularity in the Europe, Russia or Asia.

“Touching the computer screen, you’re sending a signal to throw a relay that might be located 50 feet away,” says Gray. “Whereas the pushbutton switch, those contacts are one quarter of an inch below your thumb, you can feel those contacts move. There is no doubt you have opened or closed the circuit. There are applications that probably will never make it onto a computer screen.”

As integrated cockpits embrace digital databus interfaces to major aircraft systems, we see greater demand for low profile pushbutton switches with integral sunlight readable indicators/annunciators that have the look and feel of traditional switches.— Jim Kramer, Astronics - Luminescent SystemsAirbus A350 XWB flight deck overhead panel. Photo: Airbus.Cockpit Cabin Both Other

Avionics Magazine 2015 Switches Survey

We asked our readers a few questions about their switches needs to gain some insight on the current market. One of the highlights was question number three:Do you need to acquire new switches for the cockpit or passenger area of your aircraft, or both?


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