The routing an aircraft takes to its destination depends on quite a few variables:. . 1. The type of aircraft, a twin jet has to take into account the maximum distance it is certified to fly if one engine failes, this sets the maximum distance it can be from any airport and thus the maximum distance it can be from land during any time during its flight.. 2. The route - aircraft try to follow "great circle" as being the shortest distance between any 2 points on a sphere (earth) but unfortunately politics determines which airspaces they can actually fly through and hence the shortest routes.. 3.  Other aircraft. Aircraft are routed along wide air corridors but jet aircraft need quite a narrow range of altitudes through which to fly for maximum fuel efficency and hence lower cost and hence maximum profit.  Given other traffic on the route the aircraft might end up flying a little further, but if it is the right altitude they can actually end up burning less fuel!. . Given the above, the answer is that aircraft flying from UK to Florida when flying down the east coast of the USA are actually flying quite close to a "great circle" arc - try looking at a globe and stretching a piece of string from London to Miami.