When must direction be sent to the FDC?

The requirement for sending direction to the Fire Direction Center (FDC) arises specifically when the observer-target direction changes by more than 10 degrees. This standard exists to ensure that the FDC maintains accurate positioning and fire solutions based on the shifting dynamics of the battlefield. The FDC uses the observer's direction to compute and adjust fire, making it essential that any significant alteration in direction is communicated promptly.

Maintaining this standard is crucial for safety and effectiveness; an inaccurate or outdated direction could lead to misfires or ineffective strikes, potentially jeopardizing both friendly forces and the mission. Therefore, the guideline of notifying the FDC of any substantial directional change supports operational efficiency and safety during fire missions.