What is one restriction on operating an aircraft in formation flight?

One of the key restrictions on operating an aircraft in formation flight is that no person may carry passengers for hire in such an arrangement. This regulation is in place primarily for safety and legal liability reasons. Formation flying requires precise coordination, and the additional complexity involved in operating multiple aircraft closely together is heightened when there are passengers onboard.

Carrying passengers for hire introduces potential risks that are not present when flying without passengers. The regulatory framework aims to minimize those risks by ensuring that formation flights conducted for compensation are avoided unless specifically sanctioned, typically under more stringent guidelines. This helps to ensure that safety remains the top priority during such maneuvers.

The other options address aspects of safety and operational considerations; for instance, maintaining safe distances to avoid collision hazards or ensuring agreements between pilots. However, the specific restriction regarding carrying passengers for hire directly relates to the complexities and heightened risks present in formation flying, making it a critical regulation.