aim-502

AIM

5/19/22

(b)

When an Inflight Advisory has not been

issued but observed or expected weather conditions
meet SIGMET/AIRMET criteria based on current
pilot reports and reinforced by other sources
of information about existing meteorological condi-
tions.

(c)

When observed or developing weather

conditions do not meet SIGMET, Convective
SIGMET, or AIRMET criteria; e.g., in terms of
intensity or area coverage, but current pilot reports or
other weather information sources indicate that
existing or anticipated meteorological phenomena
will adversely affect the safe flow of air traffic within
the ARTCC area of responsibility.

The following example is a CWA issued from

the Kansas City, Missouri, ARTCC. The “3” after
ZKC in the first line denotes this CWA has been
issued for the third weather phenomena to occur for
the day. The “301” in the second line denotes the
phenomena number again (3) and the issuance
number (01) for this phenomena. The CWA was
issued at 2140Z and is valid until 2340Z.

EXAMPLE

−

ZKC3 CWA 032140
ZKC CWA 301 VALID UNTIL 032340
ISOLD SVR TSTM over KCOU MOVG SWWD
10 KTS ETC.

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7. Categorical Outlooks

Categorical outlook terms, describing general

ceiling and visibility conditions for advanced
planning purposes are used only in area forecasts and
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.

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

−

LIFR CIG

−

low IFR due to low ceiling.

IFR FG

−

IFR due to visibility restricted by fog.

MVFR CIG HZ FU

−

marginal VFR due to both ceiling

and visibility restricted by haze and smoke.

IFR CIG RA WIND

−

IFR due to both low ceiling and

visibility restricted by rain; wind expected to be 25 knots or
greater.

−

8. Inflight Weather Advisory

Broadcasts

ARTCCs broadcast a Convective SIGMET,

SIGMET, AIRMET, Urgent Pilot Report, or CWA
alert once on all frequencies, except emergency
frequencies, when any part of the area described is
within 150 miles of the airspace under their
jurisdiction. These broadcasts advise pilots of the
availability of hazardous weather advisories and to
contact the nearest Flight Service facility for
additional details.

EXAMPLE

−

Attention all aircraft, SIGMET Delta Three, from Myton

to Tuba City to Milford, severe turbulence and severe clear
icing below one zero thousand feet. Expected to continue
beyond zero three zero zero zulu.

Attention all aircraft, convective SIGMET Two Seven

Eastern. From the vicinity of Elmira to Phillipsburg.
Scattered embedded thunderstorms moving east at one
zero knots. A few intense level five cells, maximum tops four
five zero.

Attention all aircraft, Kansas City Center weather

advisory one zero three. Numerous reports of moderate to
severe icing from eight to niner thousand feet in a three zero
mile radius of St. Louis. Light or negative icing reported
from four thousand to one two thousand feet remainder of
Kansas City Center area.

NOTE

−

Terminal control facilities have the option to limit
hazardous weather information broadcast as follows:
Tower cab and approach control positions may opt to
broadcast hazardous weather information alerts only when
any part of the area described is within 50 miles of the
airspace under their jurisdiction.

REFERENCE

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FAA Order JO 7110.65, Para 2

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6, Hazardous Inflight Weather

Advisory.

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Meteorology