Originally Posted by
steved5480
The altitude at which planes (Southwest's and/or them other folk) fly has zero to do with how fast/slow the on-board WiFi is or isn't. Electricity still travels more-or-less the speed of light, whether it's going up (to the satellites) or down (to the ground stations).
The satellites are much further from the ground than the airplanes and thus have significantly higher latency than ground based systems. While latency and bandwidth aren't the same thing, high latency networks are tricky things and a small amount of packet loss can dramatically impact throughput while it is barely noticed on a low latency network.