6/17/21 

AIM 

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22.  Wind Shear PIREPs 

a. 

Because unexpected changes in wind speed and 

direction can be hazardous to aircraft operations at 
low altitudes on approach to and departing from 
airports, pilots are urged to promptly volunteer 
reports to controllers of wind shear conditions they 
encounter. An advance warning of this information 
will assist other pilots in avoiding or coping with a 
wind shear on approach or departure. 

b. 

When describing conditions, use of the terms 

“negative” or “positive” wind shear should be 
avoided. PIREPs of 

“

negative wind shear on final,” 

intended to describe loss of airspeed and lift, have 
been interpreted to mean that no wind shear was 
encountered. The recommended method for wind 
shear reporting is to state the loss or gain of airspeed 
and the altitudes at which it was encountered. 

EXAMPLE

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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

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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

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“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

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established. 

Pilots should advise ATC that they are resuming the 
previously assigned clearance or should request an 
alternate clearance. 

EXAMPLE

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“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

r 

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

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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 precipita-
tion, 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. 

Meteorology 

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