Which of the following is a jump command?

The choice "Get ready" is a recognized jump command because it is used to signal jumpers to prepare for the imminent jump. This command is typically given in the final moments before the jump to ensure that all personnel are mentally and physically prepared to exit the aircraft safely. The phrase indicates that jumpers should take their positions, check their equipment briefly, and be alert for the next instructions leading up to the jump.

In contrast, the other options, while relevant to the overall process and safety of jumping, do not function as direct jump commands. "Prepare for landing" is related to the landing phase and would come into play after a jump has already occurred. "Check parachute" refers to a crucial pre-jump action but is not a command for readiness. Similarly, "Secure equipment" is important for ensuring safety during a jump but does not specifically serve as a command to initiate or prepare for jumping. Therefore, "Get ready" stands out as a clear and direct command in the context of jump operations.