Explore a unique metropolis—a midair “city” composed of nearly a million people on flights that crisscross the world daily. Meet the hidden army working to keep the city aloft and uncover the exceptional engineering and technology that make it work.

The cockpit is rigged with cameras covering all angles of the take-off as this massive 100 ton machine hurtles down the runway. It couldn’t happen without ‘lift’, and ‘thrust’ – the two fundamental forces necessary for flight to take place. It must reach its critical speed within a matter of seconds, and once the plane has crossed this threshold, there can be no turning back.

The ‘Jet Men’ rely on the same fundamental laws of physics that underpin flight for even the biggest jet-liners. Unlike your average flight though, they start by leaping from a helicopter to build up enough speed and lift to keep them airborne. It’s a high-risk operation, and has taken years of training to achieve.

We join senior Lufthansa pilot, Captain Joachim Schwarzenberg in the cockpit to learn the secrets of navigating a massive jet through the night sky. It all relies upon a hidden system of virtual ‘waypoints’ that let pilots follow a trail of breadcrumbs through the air.

In Atlanta, we explore how airport design helps regulate people-flow in the world’s busiest airport. All manner of design techniques underpin airport layout, and help to unconsciously control passenger movements through the space. This is crucial to ensuring that the biggest airports do not become congested. Airport design guru, Jim Harding, explains the tricks of the trade.

We take flight for granted, but on any journey a hidden army of people keep your plane safe. We explore just what it takes to keep the ‘city in the sky’ airborne and safe between take-off and landing. How has flying become safer than ever before?

World’s most dangerous landing in the Himalayas – this is the final approach to Paro. Paro is the capital of Bhutan, a magical Himalayan lost kingdom. Landing here is far from easy: it lacks the modern radar equipment that helps guide planes in, so pilots land manually using visual landmarks. They fly through a narrow valley with a tight turn –the runway only becomes visible at the last moment.

Inspectors get 45 seconds to ID and pick up fallen debris, across a whole runway. The smallest stray nut or chunk of rubber could be sucked into an engine and cause serious damage – potentially putting lives at risk. So it is imperative these eagle-eyed operatives don’t miss a thing.

There are around a million people airborne at any one time. But what goes up must come down – and getting passengers safely back to earth depends on complex global networks and some astonishing technology.