Final answer:
A pilot should switch from one NAVAID to the next at the changeover point, which is usually defined in the flight plan. If not specified, standard procedures or ATC instructions are followed to determine the changeover. The operation is crucial for maintaining course and airspace management.
Step-by-step explanation:
The question you've asked pertains to aviation and navigation, specifically when a pilot should switch from one NAVAID (navigational aid) to another while flying between two facilities. Pilots use NAVAIDs to guide them along their flight path and ensure they remain on course. The appropriate time for a pilot to change over from one navigational aid to the next is generally at or slightly before reaching the changeover point (COP), which is often designated in the flight plan or can be calculated by the pilot when the distance from two NAVAIDs is equal.
It is essential for safety and efficiency in airspace management that this change is executed accurately. In cases where specific COPs are not provided, there are standard procedures and rules of thumb that pilots can follow, such as utilizing the 'halfway plus' method or adhering to instructions provided by air traffic control (ATC). Advanced avionics systems and GPS can also aid in determining the optimal changeover time.