What command is given once the observer achieves a measurable airburst during precision registration?

The command given once the observer achieves a measurable airburst during precision registration is "3 Rounds Repeat." This command is critical in established fire support practices, particularly during the registration phase, where the goal is to ensure that the observed effects from the artillery accurately mimic the intended aimpoint and result in effective firepower.

When a measurable airburst is achieved, it indicates that the shells are exploding in the right altitude above the target to maximize the effectiveness of the blast. The command to fire "3 Rounds Repeat" is used to confirm this effectiveness and ensure consistency in the impact pattern. By firing three rounds, the observer can assess the dispersion and accuracy of the fire, allowing for adjustments if necessary and ensuring that subsequent rounds follow the same trajectory and altitude for optimum efficiency.

The terminology around the number of rounds used is standardized in military practices to facilitate clear communication and ensure that units are synchronized. In contrast, commands involving fewer or greater rounds than three may not provide the depth of confirmation that is needed in this situation. Therefore, using "3 Rounds Repeat" is recognized as the best practice once an effective airburst is confirmed.