How are passengers able to access the Internet on aeroplanes?, Pg9

Key Highlights:

• Modern aeroplanes offer passenger internet access via onboard Wi-Fi, connecting through either Air-to-Ground (ATG) systems or satellite links.
• ATG systems use cellular-like towers for connectivity over land, handing off connections between towers as the plane flies.
• Satellite systems use antennas to transmit data to satellites, which relay it to ground stations, providing connectivity over land and water.
• In-flight bandwidth is generally lower than home broadband and is shared among all passengers, affecting performance based on flight, route, and provider.

Detailed Insights:

• ATG systems are effective over land with dense tower coverage but are limited over oceans, deserts, and polar regions due to fewer towers.
• Satellite systems can use geostationary orbit satellites (high latency) or low-earth orbit constellations (lower latency, higher bandwidth).
• Inside the aeroplane, the network includes a central server/router, a modem, and Wi-Fi access points, with a captive portal for authentication.
• Airlines may filter traffic by blocking high-bitrate video, compressing images, and caching web pages to manage constrained bandwidth.
• Passengers are asked to use 'airplane mode' to minimize uncontrolled radio transmissions that could interfere with aeroplane systems and cellular networks.
• In-flight internet equipment is certified and tested with avionics, using frequencies separated from critical onboard systems to prevent interference.

Scientific/Technical Concepts Involved:

• Air-to-Ground (ATG): A system where aeroplanes connect to ground-based cellular-like towers for internet access.
• Geostationary Orbit: A high circular orbit (35,786 km) where satellites remain in a fixed position relative to the Earth, causing higher latency.
• Low-Earth Orbit: An orbit (150-2,000 km) closer to Earth, reducing latency and potentially increasing bandwidth for satellite internet.
• Avionics: The electronic systems used on aircraft, including communications, navigation, and control systems.