At any one time, there are a million people airborne somewhere in the world. That equates to an entire airborne city - a ‘city in the sky’. So what does it take to run a ‘city’ at 30,000 feet? In this series, we set off around the world to uncover the invisible global networks and complex logistics that make it all possible.

Aired: 2/22/2017 | 0:53:01 | Expires: 6/5/2024