Aeronautical Information ManualChange 3 · Effective 7/9/2026
Chapter 3 · Section 1
General
5 Paragraphs3-1-1–3-1-5
3-1-1 General
There are two categories of airspace or airspace areas:
Regulatory (Class A, B, C, D and E airspace areas, restricted and prohibited areas); and
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:
Controlled,
Uncontrolled,
Special use, and
Other airspace.
The categories and types of airspace are dictated by:
The complexity or density of aircraft movements,
The nature of the operations conducted within the airspace,
The level of safety required, and
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.
3-1-2 General Dimensions of Airspace Segments
Refer to Title 14 of the U.S. Code of Federal Regulations (CFR) for specific dimensions, exceptions, geographical areas covered, exclusions, specific transponder/ADS-B or other equipment requirements, and flight operations.
3-1-3 Hierarchy of Overlapping Airspace Designations
When overlapping airspace designations apply to the same airspace, the operating rules associated with the more restrictive airspace designation apply.
For the purpose of clarification:
Class A airspace is more restrictive than Class B, Class C, Class D, Class E, or Class G airspace;
Class B airspace is more restrictive than Class C, Class D, Class E, or Class G airspace;
Class C airspace is more restrictive than Class D, Class E, or Class G airspace;
Class D airspace is more restrictive than Class E or Class G airspace; and
Class E is more restrictive than Class G airspace.
3-1-4 Basic VFR Weather Minimums
No person may operate an aircraft under basic VFR when the flight visibility is less, or at a distance from clouds that is less, than that prescribed for the corresponding altitude and class of airspace. (See TBL 3-1-1.)
NOTE
Student pilots must comply with 14 CFR section 61.89(a) (6) and (7).
Except as provided in 14 CFR section 91.157, Special VFR Weather Minimums, no person may operate an aircraft beneath the ceiling under VFR within the lateral boundaries of controlled airspace designated to the surface for an airport when the ceiling is less than 1,000 feet. (See 14 CFR section 91.155(c).)
TBL 3-1-1 Basic VFR Weather Minimums
| Class A | Not Applicable | Not Applicable |
| Class B | 3 statute miles | Clear of Clouds |
| Class C | 3 statute miles | 500 feet below1,000 feet above2,000 feet horizontal |
| Class D | 3 statute miles | 500 feet below1,000 feet above2,000 feet horizontal |
| Class ELess than 10,000 feet MSL | 3 statute miles | 500 feet below1,000 feet above2,000 feet horizontal |
| At or above 10,000 feet MSL | 5 statute miles | 1,000 feet below1,000 feet above1 statute mile horizontal |
| Class G1,200 feet or less above the surface (regardless of MSL altitude). | ||
| For aircraft other than helicopters: | ||
| Day, except as provided in §91.155(b) | 1 statute mile | Clear of clouds |
| Night, except as provided in §91.155(b) | 3 statute miles | 500 feet below1,000 feet above2,000 feet horizontal |
| For helicopters: | ||
| Day | ½ statute mile | Clear of clouds |
| Night, except as provided in §91.155(b) | 1 statute mile | Clear of clouds |
| More than 1,200 feet above the surface but less than 10,000 feet MSL. | ||
| Day | 1 statute mile | 500 feet below1,000 feet above2,000 feet horizontal |
| Night | 3 statute miles | 500 feet below1,000 feet above2,000 feet horizontal |
| More than 1,200 feet above the surface and at or above 10,000 feet MSL. | 5 statute miles | 1,000 feet below1,000 feet above1 statute mile horizontal |
3-1-5 VFR Cruising Altitudes and Flight Levels
(See TBL 3-1-2.)
TBL 3-1-2 VFR Cruising Altitudes and Flight Levels
| If your magnetic course (ground track) is: | And you are more than 3,000 feet above the surface but below 18,000 feet MSL, fly: | And you are above 18,000 feet MSL to FL 290, fly: |
|---|---|---|
| 0∘ to 179∘ | Odd thousands MSL, plus 500 feet(3,500; 5,500; 7,500, etc.) | Odd Flight Levels plus 500 feet(FL 195; FL 215; FL 235, etc.) |
| 180∘ to 359∘ | Even thousands MSL, plus 500 feet(4,500; 6,500; 8,500, etc.) | Even Flight Levels plus 500 feet(FL 185; FL 205; FL 225, etc.) |