The controlled airspace immediately surrounding an airport is primarily referred to as the Control Zone (CTR) or, in some jurisdictions like the United States, by its specific airspace classification, such as Class B, C, or D airspace. A Control Zone typically extends from the surface up to a specified altitude, often 2,500 to 5,000 feet, and is designed to protect aircraft arriving at or departing from that specific airfield. Above or adjacent to the CTR, you will often find the Terminal Control Area (TMA) or Terminal Manoeuvring Area, which is a larger block of controlled airspace used to manage the high volume of traffic merging from various directions toward the airport's approach paths. In the U.S., these are often shaped like an "inverted wedding cake," where the controlled area expands in diameter as the altitude increases. This tiered system ensures that all pilots within the vicinity are under the active guidance and surveillance of Air Traffic Control (ATC), significantly reducing the risk of mid-air collisions in these densely packed "highway" segments of the sky.