Which statement best describes a Secondary Target Line (STL)?

• A. A backup radar feed for early warning.
• B. A contingency plan for shifting fires toward a different target line.
• C. A preplanned alternative target line used to shift the orientation of fires.
• D. A weather contingency plan.

Answer: (C)

The idea being tested is what a Secondary Target Line is: a preplanned alternative target line used to shift the orientation of fires. In a gun system, fires are organized along defined target lines that point the weapons toward specific sectors or targets. An STL is built into the engagement plan so you can quickly reorient your fires to a different line when the primary line isn’t suitable—due to enemy movement, terrain, or other constraints—without reworking the entire fire control setup.

Think of it as having a ready-to-use alternate azimuth that you can switch to to keep covering the right area, maintain fire discipline, and stay coordinated with adjacent units. It’s specifically about the geometry of where you aim and fire, not about weather plans or backup feeds. So using a preplanned alternative target line to shift the orientation of fires best captures what an STL is.