Context
- In-flight Internet connectivity, once rare in the early 2010s, has now become standard on commercial aircraft worldwide.
• Aircraft now use air-to-ground (ATG) and satellite-based systems to provide Wi-Fi onboard while meeting technical and regulatory aviation safety requirements.
Key Highlights
How the system works
- The aircraft acts like a flying Wi-Fi router.
• Passenger devices (phones/laptops) → connect to Wi-Fi access points inside the cabin → which connect to the Internet through a radio backhaul link (ATG or satellite).
• Devices do NOT connect directly to ground networks.
Backhaul Technologies
| System | How It Works | Advantages | Limitations |
| Air-to-Ground (ATG) | Connects plane to upward-facing ground cellular towers via antenna under fuselage | Low latency, cheaper | Works only over land, not oceans/deserts/polar regions |
| Satellite Internet | Plane’s antenna (in hump on fuselage) connects to orbiting satellites → ground stations | Works anywhere (land/sea/remote) | Higher cost, limited spectrum, shared capacity |
- Satellite evolution:
→ Older: Geostationary (GEO) satellites, 35,786 km → high latency, slower speeds
→ Newer: Low-Earth Orbit (LEO) constellations, 150–2,000 km → lower latency, higher speeds (used by Starlink, OneWeb, etc.)
How passengers log in
- Wi-Fi network inside aircraft = like a small corporate network:
→ Central router/server + satellite/ATG modem + distributed Wi-Fi access points.
• User joins network → sees captive login/payment page → traffic forwarded via ATG/satellite link.
• Airlines may shape/filter traffic:
→ Block high-bitrate video / VoIP calls
→ Compress images and aggressively cache content
→ Prioritise lightweight browsing and messaging
Relevant Prelims Points
- Radio frequencies used for aviation Internet are chosen to avoid interference with avionics systems.
• Latency differences:
→ GEO satellites: hundreds of milliseconds
→ LEO satellites: lower latency & higher bandwidth.
• Bandwidth is shared among all passengers and sometimes across multiple aircraft served by the same satellite beam, affecting speed.
• Captive portal = page requiring authentication before internet access.
• Wi-Fi access points on aircraft are part of certified aviation systems (not consumer-grade routers).
Relevant Mains Points
Why phones must stay on Airplane Mode
- To prevent uncontrolled cellular transmissions within cabin:
→ Phones search/scanning across multiple bands
→ Strong, unpredictable emission bursts
→ Could theoretically interfere with sensitive navigation/communication frequencies.
• Also prevents phones connecting to multiple ground towers simultaneously at high altitude, which can confuse cellular networks and overload handover systems.
How aviation Internet avoids interference
- Aircraft connectivity systems are purpose-designed, certified equipment integrated with avionics.
• Engineers ensure:
→ Frequency bands separated from critical onboard systems
→ Shielded wiring/antennas to prevent signal leakage
→ Fail-safe certification to avoid disruptions to aircraft control systems.
Challenges & Future Developments
- High demand vs limited bandwidth → traffic shaping and pricing models.
• Dynamic allocation of satellite capacity and transition to next-gen LEO constellations.
• Future vision: gate-to-gate connectivity, faster speeds, and streaming-grade internet.