Which instrument is typically used to check the alignment of wings during assembly?

The use of a laser level or optical alignment tool is critical in ensuring accurate alignment of wings during assembly due to its precision and ease of use. These instruments project a straight line or point from a known plane, allowing technicians to quickly identify any misalignment in the wings relative to the fuselage and each other. The advanced technology in laser tools provides a clear visual indication of alignment which is crucial for safety and performance in aviation.

In contrast, while a plumb line can be used for vertical alignment, it lacks the precision needed for more complex alignment tasks in aviation. A ruler is useful for measuring distances but does not provide the same level of accuracy in alignment checks over longer spans, where slight errors can lead to significant issues. A caliper is designed for precise thickness measurements rather than alignment, making it unsuitable for this specific task. Overall, the precision, visibility, and efficiency of laser levels or optical tools make them the preferred choice for wing alignment during assembly.