AIM ¶ 7-1-7 — Categorical Ceiling and Visibility
AIM 7-1-7 explained: LIFR, IFR, MVFR, and VFR ceiling and visibility categories for pilot students preparing for written, oral, and checkride exams.
AIM 7-1-7 defines the categorical terms used in weather reports and forecasts to describe general ceiling and visibility. These categories help you quickly assess whether conditions are flyable for the type of flight you're planning.
The four categories are:
- LIFR (Low IFR): Ceiling less than 500 ft and/or visibility less than 1 mile.
- IFR: Ceiling 500 to less than 1,000 ft and/or visibility 1 to less than 3 miles.
- MVFR (Marginal VFR): Ceiling 1,000 to 3,000 ft and/or visibility 3 to 5 miles inclusive.
- VFR: Ceiling greater than 3,000 ft and visibility greater than 5 miles (includes sky clear).
The cause of LIFR, IFR, or MVFR is shown by ceiling or visibility restrictions, using the contraction "CIG" and/or weather and obstruction-to-vision symbols (for example, FG for fog, HZ for haze, FU for smoke, RA for rain).
If winds or gusts of 25 knots or greater are forecast during the outlook period, the word "WIND" is added — even to a VFR category. Operationally, these labels let you scan an area forecast or graphical product and instantly judge whether it's a VFR cross-country day, a marginal go/no-go, or a hard IFR scenario.
Five FAA-written-style questions. Instant explanations, every answer cites its source — no account needed.
You are flying VFR in Class E airspace at 8,500 feet MSL during the day. What are your minimum visibility and cloud clearance requirements?