How does the gunner check for mask and overhead clearance?

The correct method for checking for mask and overhead clearance is by sighting along the top of the cannon. This technique allows the gunner to visually confirm that there are no obstructions, such as trees, buildings, or other overhead structures, that could impede the trajectory of the mortar rounds. By aligning their view along the barrel, the gunner can quickly assess the immediate environment and determine if the firing path is clear.

This method is efficient because it provides a direct line of sight, allowing the gunner to immediately observe any potential hazards that could affect the mortar's performance. Other options may provide some form of awareness, but they do not give the same level of direct information about overhead clearance as sighting along the cannon does. For example, using an aiming pole may help in positioning, but it does not provide a clear view of the overhead area. Checking all around the mortar or looking through the sight could inform the gunner of nearby obstructions but lacks the precision of confirming clearance along the firing line.