The Norden Bomb Sight manual

(10) The airplane flies through the air mass al-

ways in the direction of plane heading (line of

thrust. The air mass, through which the airplane

Is lying, moves over

the ground at a definite

speed and

definite direction which

is referred to

as wind speed and wind direction.

airplane moves throuch the air mass at the lane's

speed

and is carried over the

ground in the

direction of the

wind at wind speed.