General — AIM 3-1-1 Explained

AIM Text

There are two categories of airspace or airspace areas:
1. Regulatory (Class A, B, C, D and E airspace areas, restricted and prohibited areas); and
2. Nonregulatory (military operations areas [MOA], warning areas, alert areas, controlled firing areas [CFA], and national security areas [NSA]).
  
  NOTE-
  Additional information on special use airspace (prohibited areas, restricted areas [permanent or temporary], warning areas, MOAs [permanent or temporary], alert areas, CFAs, and NSAs) may be found in Chapter 3, Airspace, Section 4, Special Use Airspace, paragraphs 3-4-1 through 3-4-8.
Within these two categories, there are four types:
1. Controlled,
2. Uncontrolled,
3. Special use, and
4. Other airspace.
The categories and types of airspace are dictated by:
1. The complexity or density of aircraft movements,
2. The nature of the operations conducted within the airspace,
3. The level of safety required, and
4. The national and public interest.
It is important that pilots be familiar with the operational requirements for each of the various types or classes of airspace. Subsequent sections will cover each class in sufficient detail to facilitate understanding.

Source: FAA Aeronautical Information Manual · current edition · paragraph 3-1-1.

The short answer

This AIM section is FAA advisory guidance that frames how U.S. airspace is organized. It explains two categories—regulatory (Class A, B, C, D, E, restricted and prohibited areas) and nonregulatory (MOAs, warning, alert, controlled firing areas, and NSAs)—and four types: controlled, uncontrolled, special use, and other airspace. It supports the operating rules in 14 CFR Part 91.

Research Notes

Common Questions

What is the difference between regulatory and nonregulatory airspace?

Per this AIM section, regulatory airspace includes Class A, B, C, D, and E areas plus restricted and prohibited areas. Nonregulatory airspace includes military operations areas (MOA), warning areas, alert areas, controlled firing areas (CFA), and national security areas (NSA).

What are the four types of airspace?

The AIM lists four types within the two categories: controlled, uncontrolled, special use, and other airspace. These types are dictated by aircraft density, the nature of operations, the level of safety required, and the national and public interest.

Why does the FAA say pilots must know each airspace class?

This advisory guidance stresses that pilots be familiar with the operational requirements for each type or class of airspace, because requirements vary by complexity, density, and operations. Subsequent AIM sections cover each class in sufficient detail to facilitate understanding.

3-1-1. General