I have travelled many times between the US and India. Once the flight leaves continental USA, it flies north, curves down over the southern tip of Greenland, over Europe, descends south over the Middle East, through Pakistan, and finally on to India.
Needless to say, this curved path is significantly longer (or at least appears so to me), therefore costs more fuel, and takes longer to traverse.
What is the reason that flights choose such longer paths? Is it the desire to stay close to land as much as possible, in the event of an emergency? Any other reasons a flight path would not be a roughly straight line between two points (ignoring local deviations such as due to weather or traffic).
The “Great Circle” route is much shorter because the Earth is wider at the equator than at the poles. This is the primary reason, since fuel conservation is the #1 concern of all major airlines.
The secondary reason (although it’s a distant second) is that flying over land is much safer than flying over vast oceans or the North/South Pole. That way, if airplane suffers a malfunction, it can easily divert to the nearest runway (such as Thule AFB, Greenland). But like I said, that’s a secondary concern – airplanes routinely fly over oceans & poles if it saves them fuel & $$$$.
Yes, it does bulge at the Equator, but that’s not the primary reason. The reason is, as was stated above, we live on a sphere, where the geometry is different from that on a flat map.
On a flat plane, the shortest distance between two points is a straight line. On a sphere, it’s a great circle. The two do not necessarily coincide. All long-distance air routes are, so far as is practical in light of national borders, great circle routes.
Stretching a string across the surface of a globe can be surprising at times, like the fact that if you wanted to fly from L.A. to Johannisberg you start out flying slightly north of due East.
The most commonly used map projection is Mercator’s, which correctly maps directions like north-east, but distorts everything else, including areas (which is why Greenland looks larger that India). When you plot these shortest lines on map using Mercator’s projection, they don’t lok the shortest because of the way that the projection distorts things.
But there are other reasons why flights don’t follow straight lines. I’ve flown between Chicago O’Hare and Seoul-Incheon: as well as travelling north of Alaska for the reasons already mentioned, the flight also deviates a little to the west just before arriving in South Korea, so that it comes into Seoul-Incheon from the north-west. The reason is obvious: to avoid flying over North Korea, which would be on the straight line between the airports after Russia and China. So sometimes politics determines flight paths.
This is usually done on a “blanket” basis, so individual flights do not have to request specific permission (are so are not subject to last-minute denial).
The number of scheduled flights that have “splashed” for lack of a reachable airfield is impressively low.
One reason is ETOPS, a set of standards for twin-engined transport aircraft that say how far (in terms of single-engine flight time) a plane can be from a landable field. (A common joke is that this stands for “Engines turn or people swim”.)
Certain remote airfields - e.g. one on Midway atoll - are maintained to allow over-ocean routes that otherwise would not conform to ETOPS.
Some countries require overflight permits ($$) while others don’t. Some that don’t require permits still charge the operator air traffic control fees.
The idea that airlines are flying routes that keep them over land is not exactly true. There are a set of rules known as ETOPS (ExTended OPerationS) that require an airliner to be with X minutes of a diversionary airport at all times in case of a fire, decompression, engine failure, or medical or other emergency. It also requires specified fire-suppression performance, oxygen equipment, etc. Both Airbus and Boeing airliners are certified to at least ETOPS-180 (except the 717), with some now certified to ETOPS-240 or ETOPS-330. The 240 and 330 minute airplanes can operate over pretty much any route, anywhere in the world, unrestricted by distance from diversionary airports.
Most of the of the world only apply ETOPS restrictions to twin-engine airplanes. The FAA imposes ETOPS standards on both two- and four-engine airplanes operating to and from US airports. Australia’s CASA has adopted similar standards. Like most things in life, this was likely a politically-driven decision by the FAA, as US carriers operate very few four-engine aircraft over routes that are affected by the rules. It helps to level the playing field between competing airplanes, namely Boeing’s twin-engine 777 and Airbus’s four-engined A340. Australia has no dog in that fight, and I believe their adoption of the more stringent rules are just because they are way out there in the middle of nowhere and they truly want the additional safety margin the rules provide.
Interesting. How do US airlines handle flying to Jamaica? If wanted to fly from NYC to Kingston, Jamaica, the flight path goes right over Cuba. Will US airlines fly over Cuba?
That great circle doesn’t go over the Middle East, though, so the factors that other people have mentioned presumably affect the route.
Re flyover fees, Russia is a notable example of charging rather high fees. You’ll notice if you follow traffic at sites like Flight Radar that flights in Europe that would pass over Russian territory often make diversions to avoid doing so. I guess this affects shorter flights more than long distance ones, though.
Good point. Midway Atoll is a very small and remote US Territory that has a 24/7 public airport more or less for emergency purposes. I don’t think there are any regular commercial flights there, but afaik if you have you own plane and are allowed in the US you can go there.
I haven’t flown to Jamaica, but I have flown Miami to Grand Cayman. I was on Cayman Airways (I have a Sir Turtle frequent flyer number!). On the trip over, we flew over Cuba.
They had mechanical problems with the plane before the trip back, and we ended up on a charter plane that was US owned. They made an announcement that the trip back would take longer, because we had to go around Cuba.