Which function is not required from RNAV equipment to assist the flight crew with lateral guidance?

The function of controlling the speed of the aircraft to reach a waypoint at a specified time is not a requirement for RNAV (Area Navigation) lateral guidance. RNAV systems primarily focus on providing lateral position guidance for the aircraft based on predefined routes and waypoints along the chosen flight path. These systems enable pilots to navigate using waypoints defined by specific coordinates, allowing for greater flexibility in routing.

While maintaining an appropriate speed is important for overall flight operations, it does not directly relate to the lateral guidance function that RNAV equipment provides. The lateral guidance function requires capabilities such as holding a specific track or offset and conforming to globally recognized geodetic standards like WGS 84 for accurate positioning. Additionally, RNAV systems are designed to execute flight plans based on the flight crew's inputs, ensuring that the aircraft remains on the correct path. However, the automated control of the aircraft's speed to meet time constraints for waypoints belongs to vertical navigation and time management, rather than lateral guidance.