Which document signifies the Plane Captain's designation?

The document that signifies the Plane Captain's designation is the 4790/158. This form is specifically used to designate personnel to the role of Plane Captain, which includes responsibilities for the overall maintenance and operational readiness of assigned aircraft. It is essential for ensuring that qualified individuals are recognized and entrusted with these critical duties, as they play a pivotal role in the safe and efficient operation of naval aviation.

Understanding the importance of the 4790/158 in the context of aviation maintenance and the roles and responsibilities of a Plane Captain highlights why this answer is correct. The other documents, while part of the broader maintenance and reporting system, do not serve the specific purpose of designating individuals for the Plane Captain role. Each forms functions with different aspects of the maintenance process, such as keeping track of maintenance practices or reporting discrepancies but does not convey the authority or designation status held by a Plane Captain.