What is the title for the Authority in Charge who has complete responsibility and accountability for all things within their command?

The title for the Authority in Charge who has complete responsibility and accountability for all things within their command is "Commanding Officer." This title specifically denotes the individual in the highest leadership position in a command, who oversees all operations and personnel. The Commanding Officer has the ultimate responsibility for decision-making and ensuring that all directives are carried out effectively within the unit. This position requires a comprehensive understanding of both strategic and tactical aspects of the command, as the Commanding Officer is held accountable for the successes and failures of the unit.

In contrast, the other titles listed do not encompass the complete scope of authority and accountability associated with a Commanding Officer. For example, a General Officer typically refers to a high-ranking officer but does not designate command of a specific unit or organization. Similarly, a Lead Engineer Officer or a Line Officer can hold significant roles but are generally responsible for specific functions or areas rather than for the command as a whole.