Try and imagine what 3,000 planes look like "lined up" in the skies over England. Go on.
Practically impossible isn't it? We're not even quite sure how big one plane is (bigger than a house, yes?), let alone several thousand.
It's an exercise that's made a good deal easier thanks to this captivating video from NATS, an air traffic control management group. Their systems handle the 1.2 million flights that arrive in the skies over London each year - a 24 hour period of which has been represented by glowing lines and sparking dots.
Just where they plan on squeezing in those new flights for that extra London runway is beyond us...