An Introduction To Inflight Connectivity

In this era of ubiquitous connectivity, how hard can it be to get broadband Internet access to an airplane at a speed of ~1,000 kph at ~10,000 meters, sometimes in the middle of an ocean? Turns out, it's fiendishly difficult. Seriously, it's incredibly hard on a number of fronts.

For businesses operating in the Aerospace, Satellite and Defense (ASD) sector, it can be helpful to have a solid grasp on how inflight connectivity (IFC) works in order to better understand the business and legal issues that can arise in this space, whether related to buying satellite capacity, developing terms of service, or seeking to support linefit or retrofit of terminals. This article and the attached deck are intended to provide an overview of IFC basics and some of the challenges associated with this technology.

Challenge #1: Fiber isn't an option

Only wireless solutions can connect an aircraft to the Internet. This means connecting either from the ground (air-to-ground (ATG)) or from space via satellite (satcom). A challenge with ATG is the fact that the ground stations responsible for transmitting and receiving signals must be on the ground (meaning on or close to land), and its range is therefore relatively limited. As a result, access over large bodies of water isn't feasible. ATG is therefore used primarily by aircraft traveling over large land masses with dense air traffic, like the US, EU, and China. Ever wonder why your regional aircraft loses connectivity when flying from, say, Houston to Miami? Because it loses the ATG signal over the Gulf waters. All long-haul aircraft use satcom for IFC.

Challenge #2: Satcom terminals are large (and expensive)

Have you ever noticed the large oblong bump on top of an airplane, just in front of the tail? That's called a radome, and inside the radome is the satcom antenna. If an aircraft does not have a radome (which is increasingly rare these days), there will be no broadband Internet access onboard. Although the radome appears small in relation to a huge aircraft, it is actually quite large - over 2 meters long and almost a meter wide. As a result, a standard radome won't fit on smaller aircraft, leaving them to use a tail-mounted satcom antenna that has lower throughput. In addition to the radome and antenna, another main component of a satcom terminal is the modem. In general, modems are not interoperable among different IFC service providers. Changing terminals is both expensive and time-consuming. Airlines seek to minimize aircraft downtime by making changes when the aircraft is going in for its regular service. It takes years to change terminals in a large fleet.

Challenge #3: Frequency differences

Both ATG and satcom have different frequencies (bands) available for use, each with its own unique characteristics. When these characteristics fail to align with an aircraft's hardware, things can get tricky. ATG is generally one of three bands: the ISM (unlicensed) band (SmartSky in the US); cellular bands (EAN in the EU); or a licensed band (Gogo in the US). Similarly, Satcom has two available bands: the Ku band, which is the original frequency used by satcom, and the Ka band, a wider frequency band that was added when the Ku band became congested. Terminals are specific to a single band. Also, to reduce cost, most radomes are transparent to only one band. Some issues are inherent in physical characteristics of the band itself. For example, the Ka band is susceptible to rainfade (rain attenuates the signal), so Ka-based networks often need multiple ground stations in rainy areas to mitigate weather issues.

Challenge #4: Not all satellites are the same

Yet another complicating factor for IFC are the differences in satellite orbits. A geostationary (GEO) satellite is located at a fixed point about 36,000 km over the equator. At that orbit, a GEO satellite rotates along with the Earth so it is always above the same spot on Earth (hence "geostationary"), which means its beams remain focused on the same area (unless it has steerable beams, but that's a different topic).

A low-earth orbit (LEO) satellite, on the other hand, has a much lower orbit, usually in the hundreds of kilometers above the Earth (e.g., the initial Starlink constellation orbits at ~550 km - roughly 100 km above the International Space Station). As they orbit, LEO satellites constantly move over the Earth's surface, requiring an antenna to frequently change the satellite it is using (known as handoffs). The mechanically steered antennas that are used on most aircraft today are not equipped to handle such frequent handoffs.

Also, because of their low orbits, LEOs are affected by atmospheric drag, resulting in a much shorter useful life and requiring ongoing de-orbits and replacements. Meanwhile, GEOs are immune to drag and can have a useful life of decades.

Due to their fixed location, GEOs are great for maintaining dense coverage of an area and beams are designed to follow air traffic corridors. But GEOs do not cover very high latitudes where long-haul aircraft increasingly fly.

On the other hand, a LEO constellation can offer truly global coverage. But they can struggle to support areas with dense demand. In this regard, air traffic is very "lumpy" — ~90% of commercial air traffic takes place over ~10% of the Earth! GEOs are designed specifically to handle this lumpiness, whereas it takes a very dense LEO constellation to handle it.

The Business of IFC

The ASD sector is home to a broad array of businesses. Any company that is looking to expand into the IFC space should be cognizant of the challenges they will face and the types of arrangements and agreements that will be required. If you have any questions regarding IFC, please contact Don Levy at dlevy@outsidegc.com.

Don Levy is a Partner on OGC's California-based team. Don is a seasoned transactional and commercial attorney with deep experience in a wide range of technologies, including Internet/e-commerce, communications (wireless and satellite), semiconductor, software, SaaS, mobile device, market research, and entertainment/media. Previously, Don was Head of Connectivity 2.0 and Head of Corporate Development for Panasonic Avionics, a leading IFC service provider. Leveraging over 30 years of legal and business executive, Don helps technology companies efficiently and creatively navigate complex legal issues in dynamic environments.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.