This still from a WWII training film shows the HACS deflection screen operator in the foreground and the other HACS Table operators in the background. The solid line through the centre of the ellipse shows the wire aligned with the aircraft's track (moving right to left) of approximately 295 degrees; the Deflection Screen operator has his right hand on the Lateral Deflection Control which is aligning the vertical line with the ellipse, and the aircraft track wire, and he is also using his left hand to align the Vertical Deflection Control and a horizontal wire, (which cannot be seen) so that it also intersects the vertical wire at the edge of the ellipse.