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AIM 

4/20/23

 

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50

Meteorology

EXAMPLE

1.

Denver Tower, Cessna 1234 encountered wind shear, loss of 20 knots at 400.

2.

Tulsa Tower, American 721 encountered wind shear on final, gained 25 knots between 600 and 400 feet followed by loss

of 40 knots between 400 feet and surface.

1.

Pilots who are not able to report wind shear in these specific terms are encouraged to make reports in

terms of the effect upon their aircraft.

EXAMPLE

Miami Tower, Gulfstream 403 Charlie encountered an abrupt wind shear at 800 feet on final, max thrust required.

2.

Pilots using Inertial Navigation Systems (INSs) should report the wind and altitude both above and below

the shear level.

c.

Wind Shear Escape

1.

Pilots should report to ATC when they are performing a wind shear escape maneuver. This report should

be made as soon as practicable, but not until aircraft safety and control is assured, which may not be satisfied
until the aircraft is clear of the wind shear or microburst. ATC should provide safety alerts and traffic advisories,
as appropriate.

EXAMPLE

“Denver Tower, United 1154

wind shear escape.

2.

Once the pilot initiates a wind shear escape maneuver, ATC is not responsible for providing approved

separation between the aircraft and any other aircraft, airspace, terrain, or obstacle until the pilot reports that the
escape procedure is complete and approved separation has been re

established. Pilots should advise ATC that

they are resuming the previously assigned clearance or should request an alternate clearance.

EXAMPLE

“Denver Tower, United ll54

wind shear escape complete, resuming last ass

i

gned heading/(name) DP/clea

r

ance

.

or

“Denver Tower, United ll54

wind shear escape complete, request furthe

instructions

.

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23. Clear Air Turbulence (CAT) PIREPs

CAT has become a very serious operational factor to flight operations at all levels and especially to jet traffic
flying in excess of 15,000 feet. The best available information on this phenomenon must come from pilots via
the PIREP reporting procedures. All pilots encountering CAT conditions are urgently requested to report time,
location, and intensity (light, moderate, severe, or extreme) of the element to the FAA facility with which they
are maintaining radio contact. If time and conditions permit, elements should be reported according to the
standards for other PIREPs and position reports.

REFERENCE

AIM, Para 7

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21, PIREPs Relating to Turbulence.

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24. Microbursts

a.

Relatively recent meteorological studies have confirmed the existence of microburst phenomenon.

Microbursts are small scale intense downdrafts which, on reaching the surface, spread outward in all directions
from the downdraft center. This causes the presence of both vertical and horizontal wind shears that can be
extremely hazardous to all types and categories of aircraft, especially at low altitudes. Due to their small size,
short life span, and the fact that they can occur over areas without surface precipitation, microbursts are not easily
detectable using conventional weather radar or wind shear alert systems.

b.

Parent clouds producing microburst activity can be any of the low or middle layer convective cloud types.

Note, however, that microbursts commonly occur within the heavy rain portion of thunderstorms, and in much
weaker, benign appearing convective cells that have little or no precipitation reaching the ground.