Generally, non-fighter/attack military aircraft are designed to withstand a vertical acceleration of 4G at design gross weight. For carrier landing, the specialized landing gear design attenuates the magnitude of actual impact so that higher values result in the airframe sustaining impact up to that limit. A strong driver for carrier landing impact requirements is deck heave. Without it, the impact rate of descent can be geometrically derived from the values of aircraft speed relative to ground/deck and approach angle.