[nikanj]

A quick googling tells me there are about 10000-15000 planes in the air around the world. GPS coordinates take less than 100 bytes, but let's give some headroom for plane ID, timestamp, etc.

That would mean about 1.5 megabytes per minute, globally. I think the global satellite network is easily up to the task.

[lb1lf]

The raw data rate is pretty low, but keep in mind that there's all sorts of signaling traffic going on just to establish a connection, depending on protocol requiring multiple transmit/receive cycles - which in turn means waiting. Again depending on protocol, you may also have to handle collisions (more than one transmission in the same channel at the same time) etc - while still maintaining service for the network's regular customers.

Multiple short transmissions are more taxing than a few long ones.