Which of the following is NOT a wing takeoff requirement?

In wing formation takeoff procedures, specific requirements are established to ensure safety and flight performance. A crosswind greater than 15 knots is not classified as a takeoff requirement; in fact, it can pose challenges during takeoff and may even necessitate special considerations depending on the aircraft's capabilities and pilot experience.

The other choices detail relevant conditions for safe wing formation operations. For instance, a minimum altitude of 500 feet ensures that all aircraft are operating above potential obstacles and provides sufficient vertical separation. The absence of standing water, ice, or snow is critical to prevent potential hazards that could affect the aircraft's performance during critical phases of flight. Additionally, adhering to circling minimums is essential to ensure safety during maneuvers in formation flying, helping to maintain separation and adequate visibility.

These requirements collectively support a safe and efficient wing takeoff, while the limitations regarding crosswinds are more about operational prudence rather than strict requirements.