Section 2. Pilot Weather Report (UA/UUA)
Pilot Weather Reports (PIREPs) are filed at
unscheduled times with stations having sending
capability to WMSCR for dissemination on the
Service A domestic aviation weather system. These
reports shall be entered into the system as individual
reports, not appended to a surface observation. Entry
shall only be between H+00 and H+55.
9-2-2. PREPARATION FOR
a. M1FC entry, use WY mask. (See para
b. AISR entry, use /D procedures.
c. OASIS entry, use the Transmit PIREP dialog
AFSS/FSS specialists shall actively solicit PIREPs
in conjunction with preflight and inflight communications with pilots and assure timely dissemination of
the PIREP information. Each facility should make
special efforts to obtain PIREPs on departure and
arrival weather conditions at airports within their
flight plan area.
9-2-4. PIREP DISPLAY
Maintain a PIREP display to conform with the
particular requirements of your facility. If it is posted
for internal use only, symbology may be used at the
facility's discretion. If it is displayed as a pilot
self-briefing aid, the use of contractions, such as
OVC, shall be applicable.
9-2-5. SOLICITING PIREPs
a. Solicit PIREPs for the affected area(s) when one
or more of the following weather conditions exist, are
reported, or forecast to occur:
1. Ceilings at or below 5,000 feet.
2. Visibility reported on the surface or aloft is
5 miles or less.
3. Thunderstorms and related phenomenon.
4. Turbulence of moderate degree or greater.
5. Icing of light degree or greater.
6. Wind shear.
7. Volcanic ash clouds are reported or forecast.
Pilots may forward PIREPs regarding volcanic activity
using the format described in the Volcanic Activity
Reporting Form (VAR) as depicted in the Aeronautical
Information Manual, Appendix 2.
b. Also, solicit PIREPs regardless of weather
1. An NWS or ATC facility indicates a need
because of a specific weather or flight assistance
2. Necessary to determine flying conditions
pertinent to natural hazards (mountain passes, ridges,
peaks) between the weather reporting stations.
3. The station is designated as responsible for
PIREPs in an offshore coastal area.
c. Flight watch specialists shall solicit sufficient
PIREPs to remain aware of flight conditions.
d. To solicit PIREPs within a specific area,
broadcast a request on NAVAIDs, transcribed
broadcast facilities, or a selected communications
PILOT WEATHER REPORTS ARE REQUESTED
(location/area). CONTACT (name) RADIO/FLIGHT
WATCH ON (frequency) TO REPORT THESE
9-2-6. RECORDING OF PIREP DATA
Record PIREP data directly into M1FC or OASIS, or
on FAA Form 7110-2, or on other material deemed
appropriate; e.g., 5'' x 8'' plain paper.
9-2-7. DATA TO BE INCLUDED IN PIREPs
Include the following reports of flight conditions, as
a. Height and coverage of cloud bases, tops, and
b. Flight visibility.
c. Restrictions to visibility and weather occurring
d. Air temperature and changes to temperature
with altitude or range.
e. Direction and speed of wind aloft.
f. Extent and intensity of turbulence.
FAAO JO 7110.10, Para 9-2-8.
g. Extent, type, and intensity of icing.
FAAO JO 7110.10, Para 9-2-9.
h. Weather conditions and cloud cover through
mountain passes and over ridges and peaks.
i. Location, extent, and movement of thunderstorms and/or tornadic activity.
j. Excessive winds aloft, LLWS, and other
phenomena bearing on safety and efficiency of flight.
9-2-8. REPORTING TURBULENCE IN
a. Turbulence reports should include location,
altitude, or range of altitudes, and aircraft type, and
should include whether in clouds or clear air. The
degree of turbulence, intensity, and duration
(occasional, intermittent, and continuous) is determined by the pilot. It is essential that the report is
obtained and disseminated when possible in
conformance with the U.S. Standard Turbulence
Criteria Table as follows:
1. Light. Loose objects in aircraft remain at rest.
2. Moderate. Unsecured objects are dislodged.
Occupants feel definite strains against seat belts and
3. Severe. Occupants thrown violently against
seat belts. Momentary loss of aircraft control.
Unsecured objects tossed about.
4. Extreme. Aircraft is tossed violently about,
impossible to control. May cause structural damage.
b. Report CAT or CHOP if used by the pilot to
describe the type of turbulence.
9-2-9. REPORTING ICING CONDITIONS IN
a. Icing reports shall include location, altitude or
range of altitudes, type aircraft, air temperature,
intensity, and type of icing.
b. Icing types.
1. Rime. Rough, milky, opaque ice formed by
the instantaneous freezing of small super-cooled
2. Clear. A glossy, clear or translucent ice
formed by the relatively slow freezing of large
super-cooled water droplets.
3. Mixed. A combination of rime and clear.
c. Icing intensity.
1. Trace. Ice becomes perceptible. Rate of
accumulation slightly greater than sublimation.
Deicing/anti-icing equipment is not utilized unless
encountered for an extended period of time (over
2. Light. The rate of accumulation may create a
problem if flight is prolonged in this environment
(over 1 hour). Occasional use of deicing/anti-icing
equipment removes/prevents accumulation. It does
not present a problem if deicing/anti-icing is used.
3. Moderate. The rate of accumulation is such
that even short encounters become potentially
hazardous, and use of deicing/anti-icing equipment
or diversion is necessary.
4. Severe. The rate of accumulation is such that
deicing/anti-icing equipment fails to reduce or
control the hazard. Immediate diversion is necessary.
9-2-10. MEANS USED TO SOLICIT PIREPs
Inform pilots of a need for PIREPs. The following
methods may be used to collect PIREPs:
a. During preflight weather briefings.
b. On post-flight contacts.
c. During regular air-ground contacts.
d. Broadcast a request on NAVAID frequencies.
e. Append a request on HIWAS, TIBS, VOR-
TWEB, or TWEB broadcasts.
f. Request PIREPs from air carrier and military
operations offices, military pilot-to-forecaster units,
and local aircraft operators.
g. Solicit from other air traffic facilities.
9-2-11. PIREP CLASSIFICATION
Categorize PIREPs as follows:
a. URGENT. The following weather phenomena
shall be classified as an URGENT (UUA) PIREP:
1. Tornadoes, funnel clouds, or waterspouts.
2. Severe or extreme turbulence (including clear
3. Severe icing.
5. Low level wind shear. Classify LLWS
PIREPs as UUA if the pilot reports air speed
fluctuations of 10 knots or more. Classify reports of
LLWS with air speed fluctuations less than 10 knots
as routine. If air speed fluctuation is not reported,
classify PIREP as UUA.
LLWS defined as windshear within 2,000 feet of the
6. Volcanic ash clouds.
7. Any other weather phenomena reported
which are considered by the specialist as being
hazardous, or potentially hazardous, to flight
b. ROUTINE. Classify as ROUTINE (UA) all
PIREPs received except those listed above.
9-2-12. PIREP HANDLING
Upon receipt of a PIREP, accomplish the following:
1. Deliver to the ARTCC Weather Coordinator
as soon as possible.
2. Enter on Service A at the first opportunity.
3. Use in weather briefings, as appropriate.
1. Transmit on Service A as soon as practical.
2. Broadcast in accordance with established
procedures in Chapter 2.
3. Use in weather briefings, as appropriate.
9-2-13. OFFSHORE COASTAL ROUTES
When your station has been given responsibility for
collecting offshore coastal route PIREPs:
a. Include the coastal water area when soliciting
PIREPs. At least one PIREP is required hourly
regardless of weather conditions.
b. Pacific. Hawaiian Island station areas coincide
with the Honolulu ARTCC sectors and the entire
Hawaiian area is designated as offshore areas for
The Flight Services Operations Area Office assigns
PIREP responsibility for an offshore coastal area, route,
or route segment to a specific station. The area assigned
will be within the same ARTCC area as the station, and the
station shall have adequate air-ground communications
coverage over its assigned offshore area.
9-2-14. PIREP PREPARATION
To assure proper dissemination of PIREPs to all
system users, the encoding procedures listed below
shall be followed:
a. Identify each element by a Text Element
b. Ensure each report includes TEIs for message
type, location, time, altitude/flight level, type
aircraft, and at least one other to describe the reported
c. Precede each TEI, except message type, with a
space and a solidus (/).
d. Follow each TEI, except altitude/flight level,
with a space.
e. Insert zeros in reported values when the number
of digits in the report is less than the number required
by the format.
f. Use only authorized aircraft designators and
g. In the location TEI, include any three-letter
identifier to describe locations or routes.
h. Omit entries of TEIs, except as listed in
subpara 9-2-14b, for which no data was reported.
9-2-15. PIREP FORMAT
Using TEIs as described below, prepare PIREPs for
system entry in the following format:
a. UUA or UA. Message type - Urgent or Routine
1. Location in reference to a VHF NAVAID or
an airport, using the three or four alphanumeric
identifier. If appropriate, encode the identifier, then
three digits to define a radial and three digits to define
the distance in nautical miles.
/OV KFMG233016/RM RNO 10SW
2. Route segment. Two or more fixes to describe
c. /TM. Time that the reported phenomenon
occurred or was encountered. Report time in four
d. /FL. Altitude/flight level. Enter the altitude in
hundreds of feet (MSL) where the phenomenon was
first encountered. If not known, enter UNKN. If the
aircraft was climbing or descending, enter the
appropriate contraction (DURC or DURD) in the
remarks/RM TEI. If the condition was encountered
within a layer, enter the altitude range within the
appropriate TEI describing the condition.
/FLUNKN /RM DURC
e. /TP. Type aircraft. Enter aircraft type. If not
known, enter UNKN. Icing and turbulence reports
must always include the type aircraft.
f. /SK. Sky condition. Report height of cloud
bases, tops, and cloud coverage as follows:
1. Enter the height of the base of a layer of
clouds in hundreds of feet (MSL). Enter the top of a
layer in hundreds of feet (MSL) preceded by the word
“-TOP.” If reported as clear above the highest cloud
layer, enter a space and “SKC” following the reported
/SK OVC100-TOP110/ SKC
2. Use authorized contractions for cloud cover.
3. Cloud cover amount ranges will be entered
with a hyphen and no spaces separating the amounts;
/SK BKN-OVCUNKN-TOP060/BKN120-TOP150/ SKC
4. Unknown heights are indicated by the
5. If a pilot indicates he/she is in the clouds,
enter IMC in the remarks.
/SK OVC065-TOPUNKN /RM IMC
6. When more than one layer is reported,
separate layers by a solidus (/).
g. /WX. Flight visibility and flight weather.
Report weather conditions encountered by the pilot
1. Flight visibility, if reported, will be the first
entry in the /WX field. Enter as FV followed by a
two-digit visibility value rounded down, if necessary, to the nearest whole statute mile and append
“SM” (FV03SM). If visibility is reported as
unrestricted, enter FV99SM.
2. Enter flight weather types using one or more
of the standard surface weather reporting symbols
contained in TBL 9-2-1.
Weather Type and Symbols
Drifting / Blowing Snow
Dust / Blowing Dust
Fog (vis < 5/8SM)
Hail (aprx 1/4” dia or more)
Ice Pellets/ Showers
Mist (vis 5/8SM or more)
Patchy Fog on part of Arpt
Rain / Showers
Sand / Blowing Sand
Sml Hail/Snow Pellet Showers
Sml Hail/Snow Pellets
Snow / Showers
Well developed Dust/Sand Whirls
3. Intensity of precipitation (- for light, no
qualifier for moderate, and + for heavy) shall be
indicated with precipitation types, except ice crystals
and hail, including those associated with a
thunderstorm and those of a showery nature.
4. Intensity of obscurations shall be ascribed as
moderate or + heavy for dust and sand storms only.
No intensity for blowing dust, blowing sand, or
/WX FV01SM +DS000-TOP083/ SKC /RM DURC
5. When more than one form of precipitation is
combined in the report, the dominant type shall be
/WX FV00SM +TSRAGR
/WX FV02SM BRHZ000-TOP083
6. When FC is entered in /WX, FUNNEL
CLOUD is spelled out on /RM. When +FC is entered
in /WX, TORNADO or WATERSPOUT is spelled
out in the /RM TEI.
/WX FC /RM FUNNEL CLOUD
/WX +FC /RM TORNADO or WATERSPOUT
7. When the size of hail is stated, enter in 1/4”
increments in remarks /RM TEI.
8. The proximity qualifier VC (Vicinity) is only
used with TS, FG, FC, +FC, SH, PO, BLDU, BLSA,
/WX FV02SM BLDU000-TOP083 VC W
9. When more than one type of weather is
reported enter in the following order: 1) TORNADO,
WATERSPOUT, OR FUNNEL CLOUD; 2) Thunderstorm with or without associated precipitation;
3) Weather phenomena in order of decreasing
predominance. No more than three groups in a single
10. Weather layers shall be entered with the base
and/or top of the layer when reported. Use the same
format as in the /SK TEI.
h. /TA. Air Temperature. Report outside air
temperature using two digits in degrees Celsius.
Prefix negative temperatures with an M; e.g., /TA 08
or /TA M08.
i. /WV. Wind direction and speed. Encode using
three digits to indicate wind direction (magnetic) and
two or three digits to indicate reported wind speed.
When the reported speed is less than 10 Kts use a
leading zero. The wind group will always have “KT”
j. /TB. Turbulence. Report intensity, type, and
altitude as follows:
1. Intensity. Enter duration if reported by the
pilot (intermittent, occasional continuous) and
intensity using contractions LGT, MOD, SEV, or
EXTRM. Separate a range or variation of intensity
with a hyphen; e.g., MOD-SEV. If turbulence was
forecasted, but not encountered, enter NEG.
2. Type. Enter CAT or CHOP if reported by the
3. Altitude. Report altitude only if it differs
from value reported in /FL. When a layer of
turbulence is reported, separate height values with a
hyphen. If lower or upper limits are not defined, use
BLO or ABV.
/TB LGT 040
/TB MOD-SEV BLO 080
/TB MOD-SEV CAT 350
/TB NEG 120-180
/TB MOD CHOP 220/NEG 230-280
/TB MOD CAT ABV 290
k. IC. Icing. Report intensity, type and altitude of
icing as follows:
1. Intensity. Enter intensity first using contractions TRACE, LGT, MOD, or SEV. Separate reports
of a range or variation of intensity with a hyphen. If
icing was forecast but not encountered, enter NEG.
2. Type. Enter the reported icing type as RIME,
CLR, or MX.
3. Altitude. Enter the reported icing/altitude
only if different from the value reported in the /FL
TEI. Use a hyphen to separate reported layers of
icing. Use ABV or BLO when a layer is not defined.
/IC LGT-MOD MX 085
/IC LGT RIME
/IC MOD RIME BLO 095
/IC SEV CLR 035-062
4. When icing is reported always report
temperature in the /TA TEI.
l. /RM. Remarks. Use this TEI to report a
phenomenon which is considered important but does
not fit in any of the other TEIs. This includes, but is
not limited to, low level wind shear (LLWS) reports,
thunderstorm lines, coverage and movement, size of
hail (1/4'' increments), lightning, clouds observed
but not encountered, geographical or local description of where the phenomenon occurred, and
contrails. Report hazardous weather first. Describe
LLWS to the extent possible.
1. Wind Shear. +/- 10 Kts or more fluctuations
in wind speed, within 2,000 Ft of the surface, require
an Urgent (UUA) pilot report. When Low Level Wind
Shear is entered in a pilot report enter LLWS as the
first remark in the /RM TEI. LLWS may be reported
as -, +, or +/- depending on how it effects the aircraft.
If the location is different than the /OV or /FL fields,
include the location in the remarks.
/RM LLWS +/-15 KT SFC-008 DURC RY22 JFK
2. FUNNEL CLOUD, TORNADO, and
WATERSPOUT are entered with the direction of
movement if reported.
/RM TORNADO E MOV E
3. Thunderstorm. Enter coverage (ISOL, FEW,
SCT, NMRS) and description (LN,BKN LN,SLD
LN) if reported. Follow with “TS,” the location and
movement, and the type of lightning if reported.
/RM NMRS TS S MOV E GR1/2
4. Lightning. Enter frequency (OCNL, FRQ,
CONS), followed by type (LTGIC, LTGCC,
LTGCG, LTGCA, or combinations), if reported.
/RM OCNL LTGICCG
5. Electric DischargeEnter DISCHARGE followed by the altitude.
/RM DISCHARGE 120
6. Clouds. Use remarks when clouds can be seen
but were not encountered and reported in /SK.
/RM CB E MOV N
/RM OVC BLO
7. Plain Language. If specific phraseology is not
adequate, use plain language to describe the
phenomena or local geographic locations. Include
remarks that do not fit in other TEIs like DURC,
DURD, RCA, TOP, TOC, or CONTRAILS.
/RM BUMPY VERY ROUGH RIDE
/UA/OV BIS270030/TM 1445/FL060/TP CVLT/TB
LGT /RM Donner Summit Pass
8. Volcanic Eruption. Volcanic Ash alone is an
Urgent PIREP. A report of volcanic activity shall
include as much information as possible. Include
name of the mountain, ash cloud and movement,
height of the top and bottom of the ash, etc. If received
from other than a pilot, enter Aircraft “UNKN,”
Flight Level “UNKN,” and /RM UNOFFICIAL.
UUA/OV ANC240075/TM 2110/FL370/TP DC10/WX
VA/RM VOLCANIC ERUPTION 2008Z MT AUGUSTINE
ASH 40S MOV SSE
9. The “SKYSPOTTER” program is a result of
a recommendation from the Safer Skies FAA/INDUSTRY Joint Safety Analysis and Implementation Teams. The term “SKYSPOTTER” indicates
that a pilot has received specialized training in
observing and reporting inflight weather phenomenon, pilot weather reports, or PIREPs.
(a) When the FSS Air Traffic Control
Specialist receives a PIREP from a pilot identifying
themselves as a “SKYSPOTTER” aircraft, the
additional comment “/AWC” shall be added at the
end of the remarks section of the PIREP.
PIREP Text/RM Text/AWC
9-2-16. PIREP ENCODING
PIREPs shall be coded to ensure the PIREP is stored
and subsequently distributed with the surface
observation location nearest the condition being
reported. If more than one SA location is appropriate,
select the location that provides the greatest
distribution and/or prominence, such as a major hub
9-2-17. PIREP ORDER
Prepare PIREPs by routes from the reported location
to an adjacent location, if possible. Start a multiple
PIREP transmission with the most northerly route
and progress clockwise. Place each PIREP on a
UA/OV MRB045030/TM 1645/FL060
/TP UNKN /SK OVC055
UA/OV MRB-DCA/TM 1630/FL090/TP
AEST /RM BTWN LYRS 090
UA/OV MRB-EKN/TM 1640/FL060/TP
P28R /SK BKN-OVC020-TOP040/RM