There are around a million people airborne at any one time and keeping that number of people safely aloft depends on complex global networks and astonishing technology that stretches our ingenuity to the absolute limit.

In this programme, science broadcaster Dallas Campbell and Dr Hannah Fry explore just what it takes to keep this city in the sky safe between take-off and landing. Dallas discovers how pilots find their way across thousands of miles of sky in the dead of night. Hannah meets the air traffic controllers who are responsible for the busiest airspace in the world - over Atlanta in south east America - and reveals just what is involved in co-ordinating the 100,000 flights that cross the globe every day, while avoiding collisions.

And it is not all about the planes themselves - whether it is the care of 64 horses that regularly fly around the globe to compete in showjumping competitions or inflight medical advice from ER doctors in Phoenix for passengers who fall ill at 35,000 feet. You will never look at your time aloft in the same way again. Show less