Coding classes in Bedfordshire

The learner takes 33 destinations from Luton's published list, looks up each airport's latitude and longitude in the OurAirports open dataset, and computes the great-circle distance: the length of the shortest path over the surface of a sphere, using the haversine formula. Then they compute two more things for each route. The initial bearing is the compass heading a plane sets off on. The rhumb line is the path that keeps one compass heading the whole way, which is what a straight line on a standard map looks like.

The last column is what you get by treating latitude and longitude as if they were an ordinary square grid, 111 km per degree in both directions. It is wrong everywhere, and worst for routes that run east-west at high latitude, because a degree of longitude shrinks as you go north. Yerevan comes out 42 per cent too far. Reykjavik comes out further than Tromso, when in fact Reykjavik, at 1,862 km, is the nearer of the two by more than 350 km.

The bearing column hides the biggest surprise. A plane leaving Luton for Tbilisi sets off almost exactly due east, at 90.3 degrees. A plane leaving Tbilisi for Luton sets off at 304.3 degrees, not the 270.3 you would get by simply turning round. On a sphere, the shortest path keeps changing its compass heading. A pilot who instead held one heading the whole way, the rhumb line, would fly 3,619 km instead of 3,568, an extra 51 km for the comfort of never turning the wheel.

So a Bedfordshire teenager should learn to code in 2026 to understand the geometry inside the apps they use, and to catch the moment an answer quietly assumes the world is flat. The longer argument is in why teenagers should still learn to code in 2026.