The flight directors provide information for the pilot to join a desired path with the optimum attitude. Movement of the roll command bar to the left or right requires rolling the aeroplane to the left or right, in order to centre the command bar, and to satisfy the computed command. When centred, the command bar indicates the achievement of the required attitude.

The HSI indicates the position of the desired track in relation to your position. Therefore, if the HSI indicates a left deviation, it means that the desired track is left of the aircraft.

• In this case, if the flight director shows a right deflection it means that the aircraft needs a slight correction to the right in order to intercept the desired track in the most efficient way. This would be common, for instance, shortly before reaching the desired radial - the flight director will move right so that the aircraft doesn't overshoot the desired track. However, the HSI would still show a left deflection.