This data visualization of air traffic in Europe is brought to you by National Air Traffic Services (NATS), the main air navigation service provider in the United Kingdom. It visualizes the airspace over a typical 24-hour period in the summertime using real flight data. Note the intensity from Heathrow (the busiest international airport in Europe) as compared to Gatwick (the busiest single runway airport in the world).
Find out more at nats.aero and nats.aero/blog