Final answer:
Aircraft should be separated by 3 nautical miles if their courses diverge immediately after departure. This is related to air traffic control standards in Aeronautical Engineering.
Step-by-step explanation:
The question deals with the separation required between departing aircraft if their courses diverge immediately after departure. The correct separation in this context is typically 3 nautical miles. However, this is a subject to regulation changes and specific airport procedures, so it is essential for air traffic controllers and pilots to be aware of the current standards and procedures at their particular airport and airspace. The subject of the question is Engineering, specifically within the discipline of Aeronautical Engineering, dealing with air traffic control separation standards.