Air Traffic Control

The UK air traffic control centre  used to be at Heathrow. It's now at
Swanwick on the Hamble river, not far from Southampton in a huge modern
building. Visiting it was fascinating.

From this building all commercial as well as some, generally larger, private flights - are controlled and organised. In a vast room of computer screens, something like five thousand flights a day get delivered to and from airports all
round the world in and out of the UK. Watching the blips on the screen, particularly around Heathrow, you see how the controllers have to concentrate.

I learnt something about 'slots' - as in 'I'm sorry Ladies and Gentlemen
but we have lost our slot and will now be arriving fifteen minutes later
than scheduled'. I had always assumed that this was about taking off and
that the slot referred to the aeroplane's order in the take-off queue. In
fact, it is about when you land.

The ideal commercial flight is when you take off, climb to the cruising
altitude and land without any circling. Circling costs money. The problem
is that there are choke-points throughout the day - particularly in the
morning between 7am and 10am which is when every red-eyed businessman wants to arrive in London. The problem is that Heathrow can 'only' manage a
landing every seventy seconds so the challenge is to make sure that, with all the known knowns – speed, wind direction and distance – that each flight hits their place in the queue at exactly the right time. You see this graphically in bar-charts on screens as all the data of each scheduled flight is entered and the take off time given out - presumably by computer - as this would be a human challenge indeed when you see the numbers of flights and imagine them in three dimensions.

I now look at the orderly procession of jets over London with new eyes.