Why your flight to London goes over Greenland

Pull up the flight path tool for Los Angeles to London and the route arcs high across Canada and the tip of Greenland. On the wall map it looks like a detour. On the globe, it's the shortest possible line.

Great circles

The Earth is a sphere, and the shortest path between two points on a sphere is a great circle — the circle you'd get by slicing the sphere exactly through its centre and both points. On a flat map, where the poles are stretched to the width of the equator, a great circle between two mid-latitude cities bends toward the nearest pole.

Los Angeles and London are both at roughly the same latitude. The "straight" east-west line between them along the 45th parallel is about 9,400 km. The great circle is about 8,760 km. Over an 11-hour flight, that's 40 minutes and several tonnes of fuel.

The effect grows with distance. New York to Hong Kong on a great circle crosses the Arctic; the "obvious" westward route over the Pacific is nearly 2,000 km longer.

Why the actual track isn't the great circle either

Open a flight tracker and the real path wanders. Four reasons:

Wind. The jet streams blow west-to-east at 150–300 km/h at cruising altitude. Eastbound flights ride them; westbound flights route around them. Every day, airlines compute "wind-optimal" tracks that may lie hundreds of kilometres from the great circle. Across the North Atlantic, these become the published organised track system, which shifts daily.

Airspace. Countries charge overflight fees and some close their skies entirely. Since 2022, most Western carriers route around Russian airspace, which turned some Europe–East Asia flights from ten hours into twelve and killed several routes outright. Conflict zones in the Middle East move routes week to week.

ETOPS. Twin-engine aircraft must stay within a certain flying time of a diversion airport in case one engine fails. Modern jets are certified for 180 minutes or more, which opens almost the whole globe — but the rule still shapes some Pacific and polar routings.

Weather and traffic. Thunderstorms, volcanic ash and congested airspace all push flights off the plan in real time.

What this means for you

• A flight's scheduled duration includes typical winds. Westbound long-haul flights are scheduled longer than eastbound ones on the same route — sometimes by over an hour.
• A longer-than-expected routing shown on a tracker is usually wind or airspace, not a problem.
• The distance on your frequent-flyer statement is normally the great-circle distance between the airports, regardless of the path flown.

Try a few routes in the flight path tool. Watching Sydney–Dallas or Delhi–San Francisco curve across the top of the map makes the geometry obvious in a way no paragraph can.