In-flight connectivity has reached new heights for aircraft, including military jets and unmanned aerial vehicles. It’s not just about increased bandwidth from satellites—it’s also about leveraging lighter, faster fiber optic cables within aircraft. While your work as electrical contractors is earthbound, here’s a (mile-high) peek into what goes on in the stratosphere and beyond.
Fiber optic cable
GoGo’s air-to-ground system was the first installed across airline fleets in the United States—though it was a very small frequency band that was not able to deliver a lot of bandwidth to aircraft, said Jeremy Moore, product manager for aerospace fiber optic business development at W.L. Gore and Associates, Newark, Del.
The latest advancement was the introduction of satellite communications using antenna arrays installed on top of aircraft fuselages, which allowed a substantial increase in bandwidth—from a few megabits per second (Mbps) to 40, 50 or even 100 Mbps, Moore said.
“With that has come the development of a better system to drive data back and forth within aircraft using fiber optic cables,” he said. “Data is transmitted from satellites down to a box that converts the signal, and then is distributed to passengers within the aircraft via a wireless router.”
Passengers’ expectations for connectivity on commercial aircraft have vastly increased, Moore said. They now expect to watch Netflix movies, quickly download in-flight entertainment, work online or attend meetings on Microsoft Teams or Zoom.
“All of this content is high-resolution, which takes up a lot of data and storage,” he said. “Even though the data is locally stored on the aircraft, you have to move the data around the aircraft, and fiber optics can help enable that further.”
Previously, aircraft data links could be handled by copper, which is more durable and rugged, but inherently has limitations moving large amounts of signal, Moore said. Increased connectivity needs require larger amounts of data to be pushed around on aircraft using copper. It shortens the use-length for copper as larger bandwidth protocols get designed in, or alternatively, increases the size and weight of the copper.
“Before, you could run a two-pair ethernet to get the signal you need, but now you have to have more or larger conductors, which makes the system heavier and takes up more space in the aircraft,” he said. “That’s the tipping point when aircraft manufacturers became much more attuned to using fiber, which is lighter and faster, with low latency.”
Fiber optics—the bare glass—is more fragile than copper, but Gore developed a packaging for the glass that includes a crush-resistant PEEK layer under the jacket, said Marc Simms, vice president of sales at Cotsworks Inc., Highland Heights, Ohio. Cotsworks manufactures assembled cables and cable harnesses for Gore and its customers.
“This way, fiber can now be run reliably in the aircraft’s backbone, and even move into areas that it couldn’t have before,” Simms said. “For example, seat connectivity—we even have systems that are now bringing fiber to overhead lamps to transmit Li-Fi down to each seat.”
In the defense realm
The large amount of data required for aerospace systems, including high-resolution videos from aircraft and UAVs, needs to be transmitted quickly with no latency and great reliability so people on the ground can see information and video in real time, Moore said.
“Connectivity is probably the most important advancement in military aircraft since the advent of jet engines,” Simms said. “Fourth- and fifth-generation aircraft with different networks are now pushing a massive amount of data, including passing terabytes of data aircraft-to-aircraft, aircraft-to-ground. We now have UAVs that fly alongside aircraft as a remotely piloted wingman. The Loyal Wingman project is an example of this, creating an entire ecosystem for total battlefield awareness. The only way to do that is by using high-speed fiber optics.”
There are a lot of in-flight Wi-Fi-type systems, but the choice becomes a cost-benefit issue as fuel prices and installation costs rise, said Clint Schlosser, a product manager at TE Connectivity Ltd., Berwyn, Pa., who is based in Middletown, Pa.
“There’s a certain upper limit of what you can do inside of an aircraft—it’s all about size, weight and power when deciding the things you can do,” he said.
Traditional ethernet is either four or eight wires, but it gets pretty weighty when hundreds or thousands of those cables are run throughout an aircraft, he said. It also takes a lot more power, so the entire system architecture starts to get burdened.
“You can mitigate that by using fewer wires,” Schlosser said. “That’s where the 369 single-pair connector and single-pair ethernet cable allows airlines to go from a four-wire or eight-wire solution down to two.”
However, it also puts some of the burden on the silicon chips, essentially creating an extra layer to the ethernet stack.
“It’s saying, ‘Hey, we’re going to serialize this information,’ and so we need a little bit higher bandwidth out of that channel—the channel being the connector and the wire working together as a pair,” he said. “That’s where TE Connectivity comes in with single-pair ethernet solutions.”
TE’s solution was selected for the Aeronautical Radio Inc. standard to be used in future in-flight entertainment solutions.
Adoption of fifth-generation in-flight entertainment is in the very early stages, because protocols and security are still being defined, Schlosser said. The first waves of adoption are taking place on business class in commercial aircraft and small business jets.
“At this point, we’re going to get a step function up in bandwidth, but this is the first time I’m really seeing manufacturers attacking the size, weight and power of it as well,” he said. “In the past, it was about adding more connectivity, but they really weren’t thinking how they were going to fit all of this in the aircraft. They’re starting to shift their thinking of not only does it have to perform, but it has to do all these other things, like use less fuel.”
Airlines increasingly understand that matching demand for in-flight connectivity with supply over busy hubs is a primary challenge, said Don Buchman, vice president and general manager for commercial aviation at Viasat Inc., Carlsbad, Calif.
“Both the capacity density and flexibility of Viasat’s current satellite network can meet this demand,” Buchman said. “Flexible capacity means Viasat can concentrate capacity in highly congested air corridors or hubs so the connectivity experience remains consistent for each passenger.”
For business aviation, the company recently introduced Viasat Select. With Ka-band service plans, business jet operators can benefit from in-flight connectivity with speeds greater than 20 Mbps, Buchman said. Some operators with Viasat Ka-band IFC have reported speeds greater than 80 Mbps.
“That level of connectivity … allows all passengers to enjoy in-flight applications such as video conferencing; streaming music, video and TV; corporate VPN access and more during all phases of flight, including taxi, takeoff and landing,” Buchman said.
With each generation of Viasat satellites, the company typically adds an order of magnitude for the amount of capacity per satellite, he said. The ViaSat-3 satellites, which will start launching later in 2022, will each have more than 1,000 Gbps (or 1 terabit per second) of capacity.
“So for the in-flight connectivity experience, the future is bright,” Buchman said.
Viasat is also leveraging satellite connectivity to continue “unlocking algorithmic possibilities” that help the airlines operationally, he said. This can include applications for the crew, or predictive maintenance with all the data that is being derived from equipment on board.
“We’re in a position to leverage an ecosystem of valuable solutions such as storage, CPU and connectivity, among other things, to drive operational leverage,” Buchman said. “This adds value for the airlines, and, ultimately, will benefit the passengers as well.”