Final answer:
The radar separation for a Heavy aircraft behind another Heavy is typically 4 nautical miles or more, although actual requirements can vary based on various factors such as airspace and radar system capabilities.
Step-by-step explanation:
The question on radar separation for aircraft in a radar environment when a Heavy is behind a Heavy relates to standard air traffic control procedures for maintaining safe distances between large aircraft, known as Heavy due to their significant weight and potential for creating wake turbulence. Air traffic control rules often specify minimum separation requirements based on the category of the aircraft and the airspace in which they operate. For Heavy behind a Heavy, in many cases, the horizontal radar separation is typically 4 nautical miles or more. Factors such as airspace congestion, the capabilities of the radar system, and other control procedure modifications can also affect the required separation.