What is a necessary condition for a KIO call in ET?

A KIO (Keep In Sight) call is an important communication procedure used in formation flying to ensure the safety and integrity of the formation. It is called when a pilot perceives a risk of losing visual contact with other aircraft in the formation, which is critical to maintaining safety and coordination.

The condition of violating the 300 ft safety bubble is pivotal because this bubble refers to the minimum vertical separation that must be maintained between aircraft in formation flying to prevent collisions. If a pilot finds themselves breaching this safety margin, it is a clear indicator that visual contact with other formations may be at risk, necessitating a KIO call to alert all members of the formation to regain sight of one another and ensure safety.

While other options may seem relevant to flight safety and operations, they do not specifically pertain to the immediate necessity for a KIO call in the context of formation flying within the T-6 training environment. Maintaining a safety bubble is fundamental to avoiding collisions and ensuring that all pilots can react appropriately to maintain visual reference, making it the correct choice in this scenario.