How many personnel are absolutely necessary to run the APU?

The correct answer reflects the standard procedure for operating the Auxiliary Power Unit (APU) of the C-130J. To safely and effectively run the APU, two personnel are required. This ensures that one individual can focus on the operation and monitoring of the APU, while the second person serves as an additional safety observer or can manage communication with other team members and pilots.

Having two personnel is particularly important for ensuring safety protocols are followed, as well as for addressing any immediate issues that might arise during the APU operation, which might include monitoring different indicators and handling emergency situations if they occur. The presence of both individuals ensures adequate situational awareness and allows for teamwork in managing the aircraft's systems, contributing to a higher operational standard and safety margin during APU use.