I very much doubt that this has been dreamt up by Channel 4. I know of a guy, US Navy test pilot, who dreamt up this a few years ago, but could not raise the finance and/nor the permissions. I believe he had planned to use a 727, so they could drop out the back door. I am willing to bet, oh, at least £1.50, that this is this guy again (I can't remember his name at the moment), and that he has been trawling round for some financial support.
Note that I do not necessarily agree with it, I think it is a barking idea. I will, of course, watch it.
Oh, and for all those people that slag off Channel 4, and their viewers. Don't bloomin' well watch it then!