This (Air-to-Ground) is what Gogo does, using EV-DO Rev A.

http://en.wikipedia.org/wiki/Gogo_Inflight_Internet

Last couple flights I've usually seen latency between 300ms and 3500ms, 8-10% packet loss. They also seem to use Squid proxy, which doesn't understand WebSockets.

This is _exactly_ what Aircell does in the US. I'm not sure what spectra they're using, but the bandwidth would likely be quite variable, as planes with non-directional antennas will interact with one another over wide areas. Weather could also play a part, depending on the frequency.

Tracking aircraft is not practical unless you're going to use a phased array, and the problem you'll run into then is how large the cells are when you're pointing towards the sky, reducing spectrum separation.

Why is tracking aircraft impractical? In university I was involved in building an antenna that would track a LEO satellite (a bit crudely, though), with a pass taking about 15 minutes - that's pretty similar to a pass by a full-altitude aircraft. The main impracticality I can see is that you'll need an antenna pr. aircraft in range.

If you want to track a number of aircraft, and not require an antenna/dish per each or have resultant mechanical breakdowns, phased array antennas are the best solution.

Thanks for responding.