What comes after the command 'Hook up' in a sequence of jump commands?

The command that follows 'Hook up' in the sequence of jump commands is 'Check static lines.' After the jumpers have hooked up their static lines, it is critical to ensure that these lines are secure and properly connected for safety during the jump. This step is vital as the static line is what will deploy the parachute upon exit from the aircraft, and any issues with it could lead to serious consequences.

Conducting a thorough check of the static lines helps ensure that everything is functioning as it should before proceeding with the jump, making it a key part of the jump preparation process. This pragmatic approach to safety is essential in airborne operations, as it allows for the early identification of potential problems that could compromise the jumpers' safety.

While other options relate to jump preparations, they occur either before or after the static line check in the established sequence of commands. Thus, 'Check static lines' rightly follows 'Hook up.'