Where does the Internet on planes and trains come from?

Features of Wi-Fi on board an aircraft

Wi-Fi on an aircraft usually becomes available after the aircraft has reached an altitude of over 3 000 - 3 500 metres. This is due to several factors:

1. Safety and regulation. During take-off and landing (at low altitudes), airlines restrict the use of electronic devices due to possible interference with the aircraft's navigation systems. At low altitudes, the aircraft also actively interacts with airfield systems, so to avoid risks, all communication systems, including Wi-Fi, are usually turned off.
2. Switching to stable flight mode. Once a stable flight altitude has been reached, when the aircraft reaches a certain level (usually above 3 000 metres), the onboard system can activate Wi-Fi without any risk to safety.

Wireless Internet connectivity on passenger aircraft can be achieved in several ways:

1. «Air-to-Ground» (ATG). This technology uses a network of mobile towers on the ground to provide a connection between the aircraft and the Internet. The aircraft connects to the nearest tower and automatically switches to other towers as it moves through the air, providing a more stable connection. This is similar to how a smartphone connects to different Wi-Fi routers in a large apartment as you move around it.

Problems and limitations of ATG:

1. Connection speed. ATG typically provides a significantly slower connection compared to other technologies, such as satellite Internet. ATG speeds are typically around 3 Mbps, which limits the ability to watch high-quality video or use speed-intensive applications.
2. Limited coverage range. ATG only works on land or in close proximity to the coast. If an aircraft is flying over the ocean or sea, the connection may be lost because the towers on the ground are not accessible.
3. Interference and reliability. Compared to satellite communications, ATG may experience more interference, for example due to weather conditions or physical objects on the ground.

ATG technology is still used in a number of regions where other infrastructure is lacking or where it is cheaper to maintain mobile communication towers than to invest in satellite systems. It is mainly used for shorter flights, which allows communication with towers on the ground to be maintained.

2. Satellite communication. This is the only reliable technology at altitudes above 10 km. Modern aircraft increasingly use satellite communication because it provides a more stable connection without being tied to the aircraft's location. Systems such as Inmarsat, Iridium, and SpaceX Starlink provide connectivity even over oceans or inaccessible areas.

How satellite Internet works on an aircraft:

• The aircraft connects to satellites that are located very high in space, in a special orbit. These satellites transmit signals to the ground and receive information from it.
• Special antennas are mounted on the upper part of the aircraft (usually on the roof of the fuselage) to receive the satellite signal. After receiving the signal, special routers distribute Wi-Fi throughout the cabin.

Depending on which satellites (geostationary or low-orbit) the antennas communicate with, there are two types of satellite Internet:

• GEO (geostationary) — high latency (300-600 ms), average speed.
• LEO (low-orbit, e.g. Starlink) — lower latency (~50 ms), higher speed.

Advantages of satellite technology:

• Coverage anywhere.  You can be anywhere in the world and still have access to the Internet.
• High level of stability. This is because the satellite signal does not depend on local infrastructure (e.g., the availability of base stations).

Disadvantages of satellite technology:

1. Internet speed. It is not as fast as on the ground because the aircraft is moving quickly and flying at high altitude.
2. Equipment limitations. Not all aircraft are equipped with the latest satellite systems, so connection speed and quality may vary.

Global airlines such as Qatar Airways, Emirates, and Lufthansa already have satellite Internet on all international flights. In Ukraine, Wi-Fi on planes is gradually appearing — the first to offer it were airlines serving long-haul routes. Some international flights from Ukraine (e.g., UIA, SkyUp) already offered Internet on board before the full-scale invasion. However, it was not available on all routes and was not always free. In addition, the Internet speed did not meet high standards.

In the future, airlines plan to use «pico-cell» technology on flights over Europe. It works on the basis of special equipment that will allow passengers not only to use the Internet, but also to make calls, send messages and communicate as they would on a regular mobile network, only in the sky.

How Wi-Fi works on trains

The source of Internet access on trains is usually mobile communications (LTE/4G or already 5G). The train is equipped with several external antennas (most often on the roof of the carriages) that provide connection to mobile operators. The signal is then sent to a central on-board Wi-Fi router and distributed to passengers via Wi-Fi access points in each carriage. Connection to the Wi-Fi network is usually via an authorization portal. It all works like a mobile router, but is much more powerful and adapted to high-speed travel.

For example, let's consider how to connect to Wi-Fi on Intercity trains:

• The train connects to the mobile network of a telecommunications operator (e.g. 4G or 5G) using special antennas that receive signals from base stations along the route.
• The received mobile signal is sent to the on-board Wi-Fi router.
• The router creates a local wireless network (WLAN) that is broadcast throughout the train.
• Passengers see the available Wi-Fi network and connect to it as they would to a regular network at home or in a café.
• After connecting to the Wi-Fi network, an on-board portal (portal.uz.com.ua) opens, providing access to basic information and the Internet itself.

Features of Internet access on trains:

• Wi-Fi speed depends on the quality of the mobile signal received by the train, which in turn depends on the distance to the tower and the presence of obstacles along the route.
• Some routes have better coverage than others (especially in mountainous or sparsely populated areas).
• Multiple operators are often aggregated to avoid «dead zones».
• Unlike home Wi-Fi, trains often have an on-board portal that may contain timetables, menus and other travel information.
• A certain traffic limit or Internet speed is often provided to ensure stable network performance for all passengers.

There are countries in the world where Internet access on trains has become commonplace. For example, in Europe, most high-speed trains, such as the French TGV or German ICE, have long been equipped with Wi-Fi. In Japan, a country of technology, the Internet is even available on regular trains that travel at very high speeds.

In Ukraine, all passengers on high-speed trains already have access to Wi-Fi. Wireless Internet on Ukrzaliznytsia's Intercity and Intercity+ trains works thanks to Starlink, which was installed as part of a pilot project. Free traffic is provided to passengers at a certain speed, but signal stability depends on the section of the route. As satellite Internet becomes more accessible, its integration into transport is expanding.

Comparison of Wi-Fi on planes and trains

To illustrate the differences, we have compiled the main criteria for wireless Internet operation on planes and trains in a table.

*Some airlines and railway operators provide Wi-Fi to passengers free of charge, while others charge for it or impose restrictions (on speed, time, types of websites).

Why does Wi-Fi sometimes work poorly on public transport?

Even with good equipment, Wi-Fi on a plane or train can be slow. There are several objective reasons for this:

• Poor coverage (mountains, tunnels, over the sea, etc.).
• Network overload (for example, when all passengers are watching videos at the same time).
• Delays in satellite connections (especially with geostationary satellites).
• Weather conditions that can negatively affect signal stability.

Therefore, do not expect that the Internet on board transport, even under the best operating conditions, will replace a stable home connection. After all, Wi-Fi on transport is not quite the same Wi-Fi that we are used to at home or in the office. Here, it acts as a «local distributor» of the Internet, which is transported by other means — via satellites or mobile networks.

At the same time, Wi-Fi on public transport has a promising future. For example, the mass introduction of Starlink on aeroplanes promises faster, more stable Wi-Fi without delays. Mesh Wi-Fi technologies are appearing in train carriages, allowing the signal to be distributed evenly throughout the train. And the launch of 5G in Ukraine will improve Wi-Fi on trains, even in remote areas.

Having access to the Internet while flying or travelling by train is no longer a fantasy, but a reality. Despite technical challenges, modern technologies allow you to stay connected even on the road. So the next time you connect to Wi-Fi in a train carriage or on an airplane, remember how complex a journey this signal takes before it reaches your smartphone, tablet or laptop. And perhaps you will appreciate this connection a little more.