What can number 1 request if they lose sight of number 2 during the flight?

When number 1 loses sight of number 2 during flight, it is appropriate for them to request that number 2 "posit." This term is a request for number 2 to report their aircraft's position and ensure situational awareness for both pilots. This communication helps to establish where number 2 is in relation to number 1 and aids in maintaining formation flight safety.

The term "posit" specifically refers to confirming one's current position, making it a concise and direct request that prioritizes safety in formation flying. It acts as a critical tool for coordination between pilots, ensuring that both parties understand each other's positions.

In contrast, the other options, while potentially useful in different contexts, do not specifically address the intent of reestablishing visual contact and understanding positional awareness. For example, "check-in" might be used for general communication but doesn't specifically solicit positional information. "Come home" indicates a need to return to a reference point but lacks clarity about the relative location of number 2. "Report position" could also prompt information, but it lacks the succinctness and familiarity within formation flying that "posit" conveys.