True or False: Any formation crewmember can call "knock-it-off" if safety of flight is at risk.

The statement is true because in formation flying, all crewmembers have a shared responsibility for safety. If any crewmember perceives a risk to the safety of flight, they have the authority to call "knock-it-off." This call initiates a procedure where all aircraft in the formation cease maneuvering and focus on separating from each other and ensuring safety.

This emphasis on safety is a critical aspect of formation flying, as it relies on constant communication and the collective judgment of all pilots involved. Allowing any crewmember to call "knock-it-off" helps to create an environment where team members can prioritize safety without hesitation, thus preventing potential accidents or dangerous situations.

The other options inadvertently imply restrictions that could compromise safety. For instance, stating that only the lead can call this command could delay necessary actions if other crewmembers spot an issue first. Similarly, saying that it depends on the situation may suggest ambiguities that could lead to confusion in critical moments, undermining the immediate response required to maintain safety.