The air speed indicator tell us how fast we're going.

飞行速度指示器告诉我们飞行的速度。

He settled himself back and watched the rotor speed indicator creep up to 200 revolutions a minute.

他坐回原处， 看着转子速度指示器爬升至每分钟 200 转。

Unfortunately for everybody on board, neither of the pilots had access to a vertical speed indicator, which indicates the rate at which the aircraft is descending.

然而不幸的是，两名飞行员都没有垂直速度指示器，这可以用来显示飞机下降的速度。