AIM DECODED

3-1-3. Hierarchy of Overlapping Airspace Designations

AIM Text

  1. When overlapping airspace designations apply to the same airspace, the operating rules associated with the more restrictive airspace designation apply.
  2. For the purpose of clarification:
    1. Class A airspace is more restrictive than Class B, Class C, Class D, Class E, or Class G airspace;
    2. Class B airspace is more restrictive than Class C, Class D, Class E, or Class G airspace;
    3. Class C airspace is more restrictive than Class D, Class E, or Class G airspace;
    4. Class D airspace is more restrictive than Class E or Class G airspace; and
    5. Class E is more restrictive than Class G airspace.

3-1-4. Basic VFR Weather Minimums

  1. 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.)
  2. 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

    Airspace

    Flight Visibility

    Distance from Clouds

    Class A

    Not Applicable

    Not Applicable

    Class B

    3 statute miles

    Clear of Clouds

    Class C

    3 statute miles

    500 feet below
    1,000 feet above
    2,000 feet horizontal

    Class D

    3 statute miles

    500 feet below
    1,000 feet above
    2,000 feet horizontal

    Class E
    Less than 10,000 feet MSL

    3 statute miles

    500 feet below
    1,000 feet above
    2,000 feet horizontal

    At or above 10,000 feet MSL

    5 statute miles

    1,000 feet below
    1,000 feet above
    1 statute mile horizontal

    Class G
    1,200 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 below
    1,000 feet above
    2,000 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 below
    1,000 feet above
    2,000 feet horizontal

    Night

    3 statute miles

    500 feet below
    1,000 feet above
    2,000 feet horizontal

    More than 1,200 feet above the surface and at or above 10,000 feet MSL.

    5 statute miles

    1,000 feet below
    1,000 feet above
    1 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:

0to 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.)

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

Research Notes

AIM 3-1-3 covers Special Use Airspace — airspace designated for activities that may pose hazards to non-participating aircraft.

Special use airspace categories:

  • Prohibited Areas (P-XXX): Operations prohibited at all times. P-40 (Camp David), P-56 (NCR/DC), etc.
  • Restricted Areas (R-XXXX): Operations restricted when active. Military training, missile testing, etc. Released by ATC when inactive.
  • Warning Areas (W-XXX): Over water (3+ NM from coast). Similar to restricted areas but outside U.S. sovereign airspace.
  • MOAs (Military Operations Areas): Military training. Civilian aircraft can enter but should exercise caution.
  • Alert Areas: High-volume training or unusual activities. Mutual see-and-avoid responsibility.
  • Controlled Firing Areas (CFAs): Activities suspended when an aircraft approaches. Not charted because they don't affect non-participating ops.

Charting: Most special use airspace is depicted on sectional and IFR enroute charts. Effective hours, controlling agency, and other details in the AFD/Chart Supplement.

Reference: § 91.133 (Restricted and prohibited areas); § 91.165 (SUA operations); AIM 3-4.