Thus, a spy plane could not be completely invisible if it were to be used for espionage or, indeed, flown at all, since its pilots would need to know its position relative to the ground.

• 所以，如果要用来执行侦察任务，侦察机就不可能完全隐形，否则就不能飞行，因为飞行员需要知道飞机与地面的相对位置。