7-1-7 Categorical Ceiling and Visibility Conditions
AIM Chapter 7. Safety of Flight — Section 7-1, Meteorology
Official text — AIM 7-1-7
AIM — FAA OPERATIONAL GUIDANCEa. Categorical terms, describing either reported or forecast general ceiling and visibility conditions, are defined as follows:
1. LIFR (Low IFR). Ceiling less than 500 feet and/or visibility less than 1 mile.
2. IFR. Ceiling 500 to less than 1,000 feet and/or visibility 1 to less than 3 miles.
3. MVFR (Marginal VFR). Ceiling 1,000 to 3,000 feet and/or visibility 3 to 5 miles inclusive.
4. VFR. Ceiling greater than 3,000 feet and visibility greater than 5 miles; includes sky clear.
b. The cause of LIFR, IFR, or MVFR is indicated by either ceiling or visibility restrictions or both. The contraction “CIG” and/or weather and obstruction to vision symbols are used. If winds or gusts of 25 knots or greater are forecast for the outlook period, the word “WIND” is also included for all categories including VFR.
EXAMPLE— 1. LIFR CIG-low IFR due to low ceiling.
2. IFR FG-IFR due to visibility restricted by fog.
3. MVFR CIG HZ FU-marginal VFR due to both ceiling and visibility restricted by haze and smoke.
4. IFR CIG RA WIND-IFR due to both low ceiling and visibility restricted by rain; wind expected to be 25 knots or greater.
Reproduced from the FAA Aeronautical Information Manual (Basic (with Change 3)). The AIM is FAA guidance, not regulation. Verify against the official source before relying on it operationally.
Is this a regulation?
No — this is FAA guidance, not a regulation.
Aeronautical Information Manual. FAA operational guidance and recommended practices. The AIM is not regulatory, although it often explains how to comply with regulations.