What defines the operational levels of airspace and their vertical limits?

The operational levels of airspace and their vertical limits are defined by specific classifications such as Class A, B, C, D, E, and F. Each of these classes has unique rules and operational requirements that dictate which types of aircraft can operate within them and under what conditions. For example, Class A airspace generally requires pilots to operate under instrument flight rules (IFR), whereas Class B airspace has different restrictions, typically focused on larger aircraft operating near busy airports. Understanding these classifications is crucial for pilots as they navigate through different types of airspace and ensures compliance with the regulations that govern them.

The other options do not define airspace classifications directly. Standard Operating Procedures pertain more to specific organizational instructions rather than airspace structures. Flight Levels assigned by ATC refer to altitude assignments but do not encompass the full range of airspace classifications. The Aeronautical Information Manual provides information and guidance for pilots but does not create the categories of airspace itself; rather, it describes them and offers procedural information related to their usage.