What three conditions must occur to support formation flight join-up for two aircraft?

The correct response identifies the essential conditions that must be present for successful formation flight join-up between two aircraft. For a join-up to occur, it is crucial that either of the aircraft involved reports visually seeing the other. This sighting establishes situational awareness, which is vital for safety during the join-up process.

Concurrence among all pilots is equally important. It's essential that all involved pilots agree to the formation join-up to ensure that everyone is synchronized and aware of the maneuver. This collective agreement fosters better communication and reduces the risk of misunderstandings during the flight operation.

Lastly, the request must be initiated by any pilot. This allows for flexibility in the communication process and empowers any pilot to take the initiative, which can be crucial in dynamic flight environments where timely actions are needed.

In summary, confirming visual contact, ensuring all pilots are in agreement, and allowing any pilot to initiate the request are foundational elements that support safe and effective formation flight join-up.