Part 2: How Does “Wi-Fi” Connect to the Internet in the Air?

In part one, we outlined one of the mechanisms by which aircraft can connect their onboard Wi-Fi networks to the internet, which is air-to-ground (basically a fancy way to use a cellular-like network for airborne connectivity). This week, we’ll take a look at the basics of satellite communications (satcom).

There are two main satcom networks or constellations (they are in space, after all): geostationary orbit (GEO) and low earth orbit (LEO). 

GEO: large satellites cover a huge area from about 22,000 miles above the earth’s surface, matching the rotation of the earth so they appear to hover above a specific point. Enough GEO satellites can cover most of the earth and provide satcom to boats, airplanes, and other users on the surface. GEO satellites typically don’t cover the polar regions. Few aircraft fly above the South Pole, but there is air traffic over the North Pole and until recently, no coverage there. However, new GEO satellites in elliptical orbits will provide Northern Polar coverage.

The big player in GEO satcom is Viasat, which bought its main competitor Inmarsat in May 2023. At the time, Viasat provided airborne equipment (antennas and terminals) and satcom service (airtime), while Inmarsat dealt with service resellers and third-party equipment manufacturers (Honeywell is the main one). Now Viasat is working with equipment manufactures and service providers such as resellers Honeywell and Gogo, which makes its own antennas for Viasat connectivity (through its purchase of Satcom Direct in December 2024).

LEO satcom constellations are much closer to earth, just a few hundred miles, and use many more satellites than GEO. Starlink has grown into a significant player in the LEO market, now with more than 10,000 satellites providing high-speed service. The other players are EutelSat OneWeb (648 satellites, expected to grow further), Iridium (66 plus nine spares), and Amazon LEO (formerly Kuiper, 150+ satellites), which is just starting to come online. 

A big difference between GEO and LEO satcom is the type of antenna. GEO satellites use mechanically steered antennas with lots of moving parts, usually housed on top of a business jet’s vertical stabilizer but also installable on top of the fuselage on larger jets and airliners. LEO satcom uses electronically steered antennas with no moving parts, a so-called flat-panel design that is mounted on top of the fuselage. If you’ve ever seen a Starlink antenna, that is the same design.

Another difference is that GEO satcom has higher latency than LEO because the higher distance means that GEO signals take longer to move between the satellite and antenna and vice versa. In well-designed GEO systems, this isn’t always apparent to the user, but the video streaming experience with LEO might be better due to lower latency. 

Starlink and Gogo Galileo provide high-speed broadband service. Iridium, even with a new satellite constellation called Next, doesn’t have as much capacity so its service is slower but still useful for voice calls and light internet usage. Many of the Iridium-based satcom installations are used for industrial-type applications such as tracking helicopters, sending maintenance data, or for law enforcement uses.

No matter what kind of airborne connectivity system is installed, there is a concept in network systems that explains how a single system will never have as much availability as two distinct systems. With two different systems installed in an aircraft, availability goes up to greater than 99%, and many business jet owners are opting for so-called dual differential systems to ensure a high availability level. That might mean a GEO and LEO, for example, or perhaps ATG for U.S. coverage augmented by satcom for flights outside the U.S. as well as improved reliability in the U.S. 

Service for broadband satcom costs thousands of dollars per month for heavy users. Starlink’s unlimited aviation service, for example, costs $10,000 per month.