Air to Ground (ATG) vs. SATCOM: Which Is Right for Me?

November 2021

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Especially in the post-Covid world, with meetings now routinely conducted via videoconferencing, internet connectivity in the business aircraft cabin has become an absolute necessity. As such, more and more players are entering the business of providing that connectivity. The myriad choices accompanied by a proliferation of communications industry terms can be confusing to the aircraft owner or flight department manager trying to choose the best system.

The Difference between Satcom and ATG

Satellite communication (SATCOM) has been around since before men landed on the moon, though the technology has radically improved since then. While the 51 kilobits per second (kbps) data rate enjoyed by the Mercury astronauts in 1969 allowed black-and-white television to be broadcast from the moon to ground stations on Earth, it would not hold up to the data usage on multiple devices that we expect on just one aircraft today. Increases in switching speed, powerful software, and placing satellite networks in low-Earth orbit to dramatically decrease the distance that signals must travel (called latency) now enable satcom data rates in the megabits-per-second (Mbps) range.

Latency is key in data communications—especially as it affects data rates and the ability to stream video—and one way to reduce it is to keep signals closer to the ground. This is where air-to-ground (ATG) data networks come in.

“One fundamental difference between ATG and satcom is the equipment that you put on the aircraft,” explained Adam Sheppard, General Manager of In-Flight Connectivity for Honeywell Aerospace in Phoenix. “Satcom requires an antenna that mounts on the top of the aircraft and looks up at a satellite while ATG has equipment that you mount on the bottom of the aircraft that looks down at cellphone towers on the ground.”

What’s Best for You?

Both SATCOM and ATG provide broadband connectivity for business aviation. Determining which is right for you depends on your aircraft and mission.

The antennas sizes required for satcom and ATG differ greatly. Satcom packages—such as Honeywell’s JetWave system, which connects to Inmarsat’s Global Xpress Ka-band satellite network to provide speeds up to 33 Mbps—require relatively large antenna (one to three feet long) that can be mounted in the aircraft’s tail or on top of the fuselage. Long-range aircraft such as Airbus Corporate Jets, Boeing Business Jets, Gulfstreams, and Bombardier Global Expresses typically serve as the best candidates for these systems. Space must be also appointed for the system’s control boxes, modem, and router.

Air-to-ground systems, such as the SmartSky Network offered by Honeywell, use much smaller antennae mounted on the bottom of the fuselage to provide broadband capability through ground-based cellular networks, including the newest 5G. The smaller antennae allow these systems to be installed on a wide variety of business aircraft, including very light jets and turboprops. In addition, the lightweight and compact Honeywell GoDirect Router can be used with the SmartSky Network to provide up to 5G network speed, performance, and reliability on these smaller aircraft.

Another factor in satcom vs. ATG is where you typically fly. Since ATG systems require ground-based stations, their service typically ends just a few miles offshore or at the border. If your mission keeps your aircraft within the contiguous U.S., an ATG system might be all you need. But if you’re typically making international flights, satcom might be the way to go as it’s the only way to obtain uninterrupted internet service nearly anywhere in the world.

For small and medium-sized business jets flying outside the contiguous U.S., Honeywell offers a suite of Aspire satellite broadband systems, which provide data rates of up to 700 kbps.

What Do Your Passengers Require?

What your passengers typically do on the aircraft can make a difference in the type of connectivity you need. High-definition video streaming usually requires a bandwidth of at least five Mbps while streaming 4K video requires a minimum of 25 Mbps. However, all of the Honeywell offerings come with comprehensive Honeywell Forge software and support, which allows you to tweak network settings to get the most out of your connectivity dollars.

 “We have tools in our network that can shape [video] traffic,” said Sheppard. “If someone is watching a 4K movie on a smartphone screen, it’s a waste of bandwidth because the screen can’t show the 4K details. Rather than sending 4K video to that device, our filtering and traffic-shaping tools will sense that it’s a smartphone and send the video at 700 kilobits per second. It looks great to the passenger, but it’s consuming one-10th the data. We can save customers up to $150,000 a year in data just by using these tools.” 

Uploading data or videoconferencing may require satcom’s generally higher bandwidth, although customers on ATG systems can use Honeywell Forge tools to constrict meaningless traffic to allow the VIPs on board to get their work done.

“Sometimes a whole group will go out to a job site and everyone’s devices will be set to upload their photos at the same time when they connect to the aircraft’s Wi-Fi,” said Sheppard. “This can clog up the bandwidth and make the network seem slow. With Honeywell Forge, we can set filtering tools to ensure that doesn’t happen and that the important work gets the bandwidth it needs.”

Finding a Cost-effective Solution

For customers willing to pay for comprehensive solutions, Honeywell Forge can control multiple connectivity systems on the same aircraft. Some customers opt to put certain passengers and their devices on the ATG system—similar to a guest Wi-FI network—while the VIPs remain on the satcom system. This ensures that the VIPs keep the bandwidth needed to conduct business via videoconference at altitude. Others opt for both systems as a backup in case one is down temporarily.

Operators that need to keep costs down may opt for a more cost-effective ATG system, especially if most of their travel is domestic. One benefit of the SmartSky ATG network is its ability to use beamforming to send information to and from just one aircraft. This isolates the data using that bandwidth, allowing passengers on that aircraft to stream, chat, text, call, play video games, and videoconference seamlessly for much less than a satcom package with the same capability would cost.

“It's not a one-size-fits-all type of solution,” said Sheppard. “Honeywell Forge can tune your data needs to your data costs. We can tune your equipment needs to your mission needs. We can tune your passenger needs to your data speeds, and then we can tune your overall operations needs to how that data is delivered to the people on board in the most cost-effective way.”