system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can there be WiFi on an airplane? 

I'm taking a flight across the country, and my plane has WiFi. What kind of black magic is at work here?
gpt
The earlier systems, like Boeing's Conexxion, used a special kind of antenna called a phased-array antenna.  That antenna sent radio signals to a satellite in orbit which was then sent back to earth to an ISP.  Slow, but it kind of worked.  You also needed an antenna dome added to the top of the plane.

The newer systems, like Gogo, use cellular transmitters on the plane to talk to special towers on the ground.  The towers are just like your 3G/4G towers but the signals point UP instead of down at the ground around them.  Gogo is planning to add satellite transmitters later so they can handle overseas flights.

Once the signal gets to the plane it's sent to a normal wifi access point and access/billing is handled at the ISP.