(ominous music) - Officer 7-5, I have new vectors for you we're sending you to RAF Coningsby.

- [Pilot] No, we won't make that.

We need to land.

(ominous music continues) - In the first episode, we have a major plane crash.

- When we all read the script, we knew from the beginning, that was going to be one of our biggest set pieces.

- (Charlie) It's all about planning.

They start with physical elements, being very prepared that you've shot enough of the physical elements that you can help The special effects people three months, four months later.

(plane engine whirring) (plane crashing) - [Joe] We brought our designer together, we brought our stunts team together, special effects director, and just all thought how do we go huge with this and make it feel really real?

We got a real plane, cut it into pieces and brought it to our location.

Then we set a lot of it on fire and got people running around.

So I think the challenge was to make it as real as we possibly could and to be ambitious.

And that's what, that's what we did, and hopefully that's what comes across on the screen.

- There's 17 in intensive care.

Six of them are touch and go, the rest are mostly multiple fractures.

- Our approach was to make things practical as much as we could.

- We have a real plane and we break it up and we put it on the motorway.

And then we enhance that with visual effects, film, some actors, a real cockpit of a real airplane somewhere else.

We have, you know, helicopter shots, which are off the motorway, which help us place the impact of the plane.

So it's all sorts of filmed and real and created elements come together in quite a complicated package.

- [Joe] But as it happened, we've got a fantastic visual effects team, and working with them allowed us to be even more ambitious than I think we started out.

We approached the riots by trying to find the right location.

Protesters had blocked the motorway and they clash with police and army.

Ultimately we found a brilliant strip of fake motorway, which the fire service used to film on, which gave us a great sort of foreground to work in.

And then we added to that with signage to make it feel like the M25, and then bringing a lot of extras, army and vehicles to make sure that it all just comes together quickly and well.

(dramatic music)