Blur Zone

WHEN an aircraft flies at low altitude and at high speed, the terrain goes past so quickly that the pilot may be unable to see ground features clearly, particularly when he looks to either side of his aircraft. This is due to the fact that the angular velocity of the passing scene is least ahead and aft, but greatest at right angles to the line of flight. The investigation of this problem, first graphically, then by calculation, has revealed an interesting fact which may well have other applications.