[pinaceae]

that is a very good question - and thanks to the ongoing drone warfare by the US, this is being answered right now.

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

the wikipedia article above is a good entry point. note how drones were successfully used in the Vietnam war.

[cpa]

Indeed, but the specification for unmanned planes carrying 300+ people will probably be much harsher than the spec for military drones... I think that first thing we will witness is freight done by huge drones.