I do not know how much bandwidth you would need to track the entire fleet of all major airlines (even if you, say, limited yourself to international and/or flights longer than X hours/km), but worldwide tracking of automated instrumentation (I'm an earth scientist) is done regularly. A few examples:

- The iridium satellite network, which provides phone service, also provides a Short Burst Data service, which I suspect could be used for this purpose.

- The Argo network tracks thousands of ocean drifters (http://www.argos-system.org/?nocache=0.9626778103411198). Some of those drifters are using the Iridium network now.