When should you send the observer-target direction if it has changed?

The observer-target direction should be sent when it changes by more than 100 mils because this threshold ensures that the adjustment in the orientation is significant enough to warrant communication. A change of this magnitude can impact the accuracy of the artillery fire, so informing the relevant parties minimizes the risk of error. This protocol helps maintain effective coordination and ensures that the targeting data remains precise and effective for mission success.

In this context, the other thresholds mentioned, such as 10 mils, 20 mils, and 50 mils, do not capture the necessary magnitude that would influence the accuracy significantly, and therefore, would not necessitate immediate communication in the same way a change of more than 100 mils would.