Slower cruising — at about Mach 0.7, or seven-tenths the speed of sound, which is 5 percent to 10 percent slower than today's aircraft — and at higher altitudes, to save fuel.

更低速的巡航——大约0.7马赫，即音速的十分之七，比今天的飞行器低5 - 10%——并且飞行于更高海拔以节约燃油。

youdao

But it forgot to mention that at today's cruising altitudes passengers are exposed to a considerable amount of radiation, especially on transatlantic flights close to the pole.

ECONOMIST: Sweden's model economy