AIM
4/20/23
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Airport Operations
EXAMPLE
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Wind shear alert, airport wind 230 at 8, south boundary wind 170 at 20.
b.
LLWAS “network expansion,” (LLWAS NE) and LLWAS Relocation/Sustainment (LLWAS
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RS) are
systems integrated with TDWR. These systems provide the capability of detecting microburst alerts and wind
shear alerts. Controllers will issue the appropriate wind shear alerts or microburst alerts. In some of these systems
controllers also have the ability to issue wind information oriented to the threshold or departure end of the
runway.
EXAMPLE
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Runway 17 arrival microburst alert, 40 knot loss 3 mile final.
REFERENCE
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AIM, Para 7
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1
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24, Microbursts.
c.
More advanced systems are in the field or being developed such as ITWS. ITWS provides alerts for
microbursts, wind shear, and significant thunderstorm activity. ITWS displays wind information oriented to the
threshold or departure end of the runway.
d.
The WSP provides weather processor enhancements to selected Airport Surveillance Radar (ASR)
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facilities. The WSP provides Air Traffic with detection and alerting of hazardous weather such as wind shear,
microbursts, and significant thunderstorm activity. The WSP displays terminal area 6 level weather, storm cell
locations and movement, as well as the location and predicted future position and intensity of wind shifts that
may affect airport operations. Controllers will receive and issue alerts based on Areas Noted for Attention
(ARENA). An ARENA extends on the runway center line from a 3 mile final to the runway to a 2 mile departure.
e.
An airport equipped with the LLWAS, ITWS, or WSP is so indicated in the Chart Supplement U.S. under
Weather Data Sources for that particular airport.
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8. Braking Action Reports and Advisories
a.
When available, ATC furnishes pilots the quality of braking action received from pilots. The quality of
braking action is described by the terms “good,” “good to medium,” “medium,” “medium to poor,” “poor,” and
“nil.” When pilots report the quality of braking action by using the terms noted above, they should use descriptive
terms that are easily understood, such as, “braking action poor the first/last half of the runway,” together with
the particular type of aircraft.
b.
FICON NOTAMs will provide contaminant measurements for paved runways; however, a FICON
NOTAM for braking action will only be used for non
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paved runway surfaces, taxiways, and aprons. These
NOTAMs are classified according to the most critical term (“good to medium,” “medium,” “medium to poor,”
and “poor”).
1.
FICON NOTAM reporting of a braking condition for paved runway surfaces is not permissible by
Federally Obligated Airports or those airports certificated under 14 CFR Part 139.
2.
A “NIL” braking condition at these airports must be mitigated by closure of the affected surface. Do not
include the type of vehicle in the FICON NOTAM.
c.
When tower controllers receive runway braking action reports which include the terms medium, poor, or
nil, or whenever weather conditions are conducive to deteriorating or rapidly changing runway braking
conditions, the tower will include on the ATIS broadcast the statement,
“BRAKING ACTION ADVISORIES ARE
IN EFFECT.”
d.
During the time that braking action advisories are in effect, ATC will issue the most recent braking action
report for the runway in use to each arriving and departing aircraft. Pilots should be prepared for deteriorating
braking conditions and should request current runway condition information if not issued by controllers. Pilots
should also be prepared to provide a descriptive runway condition report to controllers after landing.
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9. Runway Condition Reports
a.
Aircraft braking coefficient is dependent upon the surface friction between the tires on the aircraft wheels
and the pavement surface. Less friction means less aircraft braking coefficient and less aircraft braking response.