We like to think that long distance travel times are getting shorter as modern technology enables planes to travel faster. But via Andrea James I came cross this fascinating video explanation put together by someone who looked at old flight schedules from fifty years ago and found that travel times are actually longer now than they were back then. Why is this? Part of the reason is that the increased congestion in the air and at airports means that there is longer time spent waiting for clearance and taxiing on the runways than was the case before.
But the main reason is that for most people, the main concern is the cost of travel not the time taken. It is only a very few for whom cost is not a factor and where time becomes important. But there are reasons, based on aerodynamics and the design of engines, that make the cost per passenger mile of flying most economical at speeds of 500-550 mph (800-885 km/h). The main cost in flying is not the cost of the plane but the fuel used per trip and between speeds of Mach 0.8 and Mach 1.2 (where Mach 1 is the speed of sound) is what is known as the transonic range where air drag rises dramatically. So it makes sense to stick to speeds below Mach 0.8. So if you had dreams of some day zipping across the world in a couple of hours, better give it up.
This is a very informative, nicely produced video that explains the different kinds of airplane engines and the tradeoff for each between speed and cost and why airlines choose not to use the ones that give them the most speed.