Chapter 2:  Airspace Classification, Operating Requirements, and Flight Restrictions  Introduction  Controlled Airspace Class B Airspace The two categories of airspace are: regulatory and nonregulatory. Within these two categories, there  are four types: controlled, uncontrolled, special use, and other airspace. The categories and types of  airspace are dictated by the complexity or density of aircraft movements, nature of the operations  conducted within the airspace, the level of safety required, and national and public interest.  Figure 2-1 presents a profile view of the dimensions of various classes of airspace. Controlled airspace is a generic term that covers the different classifications of airspace and defined  dimensions within which air traffic control (ATC) service is provided in accordance with the airspace  classification. Controlled airspace that is of concern to the remote pilot is: Class B airspace is generally airspace from the surface to 10,000 feet mean sea level (MSL)  surrounding the nation’s busiest airports in terms of airport operations or passenger enplanements.  The configuration of each Class B airspace area is individually tailored, consists of a surface area and  two or more layers (some Class B airspace areas resemble upside-down wedding cakes), and is  designed to contain all published instrument procedures once an aircraft enters the airspace. A  remote pilot must receive authorization from ATC before operating in the Class B airspace. Remote Pilot – Small Unmanned Aircraft Systems Study Guide  5 • Class B • Class C • Class D • Class E Figure 2-1.  Airspace profile.