I am reading some texts about WWII and English operators tell the pilots to "Steer 1-2-0". Can anyone help with the meaning of 'steer' here? Is it a synonym of 'direction', 'heading' or 'vector'?
To "steer" means to change the aircraft's track (the direction of movement of the aircraft) to a certain degree in relation to the lines of meridian (north–south lines). The units are degrees from north in a clockwise direction. North is 0°, east is 90°, south is 180°, and west is 270°. Note that, due to wind forces, track is not the same as the heading (where the nose is pointing).
The modern ATC phraseology is "Fly heading 1-2-0".