BendixKing KAC 503 User Manual
Understanding Aviation
Weather Reports
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TABLE OF CONTENTS
UNDERSTANDING METARS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
UNDERSTANDING TAFS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
UNDERSTANDING PIREPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
UNDERSTANDING AIRMETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
UNDERSTANDING SIGMETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
UNDERSTANDING CONVECTIVE SIGMETS . . . . . . . . . . . . . . . . . . .12
UNDERSTANDING ALERT WEATHER WATCHES (AWW) . . . . . . . .14
APPENDIX A COMMON WEATHER ABBREVIATIONS . . . . . . . . . .A-1
APPENDIX B INFLIGHT ADVISORY LOCATOR CHARTS . . . . . . . .B-1
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UNDERSTANDING METARS
Refer to the numbers on the following diagram to find the appropriate
descriptions.
13452678
METAR KPIT 201955Z AUTO 22015G25KT 3/4SM R28R/2600FT TSRA OVC010CB
18/16 A2992 RMK SLPO13 T01760158 PK WND 22030/15
910 11
1. Type of Report: METAR (SPECI will be seen here if this is a Special
Weather Report)
2. ICAO Station Identifier: KPIT
This is the location for which the METAR pertains.
3. Date and Time of Issue: 201955Z
The 20th day of the month at 1955Zulu or UTC.
4. AUTO indicates the reporting station is an automated station. If the
reporting station is a manned station this element will be omitted. Also,
if a report from an automated station is modified by a person this element will be omitted. “COR” indicates a corrected report.
5. Wind: 22015G25KT
220 is the 3 digit true direction to the nearest 10°. Airport advisory ser-
vice, ATIS and ATC towers report wind direction as magnetic. “VRB” in
this place indicates variable winds less than or equal to 6 knots. If wind
direction is varying more than 60° with speeds over 6 knots, an entry
similar to “180V260” will be displayed in this place. This example
actually shows wind direction varying by 80°.
15 is the 2 or 3 digit wind speed (in knots).
25 is the 2 or 3 digit wind gust speed in knots (KT) because it follows a G
(Gust).
6. Visibility: 3/4SM R28R/2600FT
3/4 indicates 3/4 statute mile (SM) visibility.
Runway Visual Range (RVR) for R28R (runway 28 right) is 2600 feet
(2600FT). An “M” in this distance number indicates visibility is less than
the lowest reportable sensor value. A “P” indicates visibility is
greater than the highest reportable sensor value.
NOTE: Only reported at those locations with certified RVR reporting capability.
Rev 1 Oct. 2003
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7. Significant Present Weather: TSRA
TS is a two letter designation for thunderstorm. Other possible desig-
nations could be as follows:
BC Patches
BL Blowing
DR Low Drifting
FZ Supercooled/Freezing
MI Shallow
PR Partial
SH Showers
The second two letter designator, RA, indicates moderate rain.
Moderate is indicated by the absence of a “+”, “-” or “VC” preceding the
designation. These preceding designations represent the following:
+ Heavy
- Light
VC In the vicinity
Other possible designations could be as follows:
BR Mist
DS Dust Storm
DU Widespread Dust
DZ Drizzle
FC Funnel Cloud
+FC Tornado/Water Spout
FG Fog
FU Smoke
GR Hail
GS Small Hail/Snow Pellets
HZ Haze
IC Ice Crystals
PE Ice Pellets
PO Dust/Sand Whirls
PY Spray
SA Sand
SG Snow Grains
SN Snow
SQ Squall
SS Sandstorm
UP Unknown Precipitation (Automated Observations)
VA Volcanic Ash
8. Sky Condition: OVC010CB
OVC indicates the sky is overcast. Cloud cover is based on the sky
being divided into eighths or octas. Overcast means the sky is 8 octas
covered. The cloud cover designators are as follows:
SKC Sky Clear
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CLR Clear below 12,000 ft. (automated observing systems)
FEW 1-2 Octas
SCT 3-4 Octas
BKN 5-7 Octas
OVC 8 octas
“VV” may also be encountered here indicating an indefinite ceiling. For
example, VV004 would indicate a vertical visibility of 400 feet.
010 indicates clouds are at 1000 feet.
CB denotes cloud type is cumulonimbus. “TCU” is another possible
designator meaning towering cumulus. CI is cirrus.
9. Temperature/Dew Point: 18/16
18 indicated the temperature is 18° Celsius. An “M” preceding the tem-
perature means the temperature is below 0° Celsius.
16 indicated the dew point is 16° Celsius. An “M” preceding the dew
point means the dew point is below 0° Celsius.
10. Altimeter Setting: A2992
A indicates the setting is in inches of mercury.
2992 is the altimeter setting. The first two digits are inches and the
second two are hundredths.
11. Remarks: RMK SLP013 T01760158 PK WND 22030/15
RMK designates the beginning of the remarks. Remarks can contain
anything, but often include the following:
SLP indicates sea level pressure in millibars from selected stations.
013 indicates pressure is 1001.3 millibars.
T01760158. Selected stations may also include a 9 place code indi-
cating temperature and dewpoint to the nearest 1/10 degree. T
denotes temperature. 0 indicates temperature is above 0° Celsius. A
“1” in this position indicates a temperature below 0° Celsius. 176 indicates a temperature of 17.6° Celsius. The next 0 indicates the dew
point is above 0° Celsius. A “1” in this position indicates a dew point
below 0° Celsius. 158 indicates a dewpoint of 15.8° Celsius.
PK WND 22030/15. Selected stations may include peak wind observations which will appear in the remarks element.
PK WND denotes peak wind.
200 indicates wind direction from 200°.
30/15 indicates a maximum instantaneous wind of 30 knots occurred at
15 minutes past the hour.
Rev 1 Oct. 2003
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UNDERSTANDING TAFS
Refer to the numbers on the following diagram to find the appropriate
descriptions.
6
1345
2
TAF KPIT 091730Z 091818 22020KT 3SM -SHRA BKN020
7
8
FM2030 30015G25KT 3SM SHRA OVC015 WS015/30045KT
19
TEMPO 2022 1/2SM TSRA OVC008CB
FM0100 27008KT 5SM -SHRA BKN020 OVC040 PROB40 0407
00000KT 1SM -RA BR
10
FM1000 22010KT 5SM -SHRA OVC020 BECMG 1315 20010KT
9
P6SM NSW SKC
11
1514131216 17 18
1. Type of Report: TAF
TAF indicates a Terminal Area Forecast. TAF AMD indicates an
amended forecast.
2. ICAO Station Identifier: KPIT
This is the airport for which the TAF pertains.
3. Date and Time of Issue: 091730Z
The 9th day of the month at 1730Zulu or UTC.
4. Date and Time Valid: 091818
The 9th day of the month, valid for 24 hours from 091800Z to 101800Z.
An amended forecast (TAF AMD) will be valid for only the time interval
remaining, usually less than 24 hours.
5. Forecast Wind: 22020KT
See #5 in the UNDERSTANDING METARs section for details.
6. Forecast Visibility: 3SM
See #6 in the UNDERSTANDING METARs section for details, except
RVR is not included in a TAF
7. Forecast Weather Phenomenon: -SHRA
See #7 in the UNDERSTANDING METARs section for details.
8. Sky Conditions: BKN020
See #8 in the UNDERSTANDING METARs section for details.
9. Beginning of Changed Forecast Conditions: FM1000
20
21
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FM denotes “from” and 1000 indicates 1000Z. “From” means a significant change in prevailing conditions is expected. The described conditions follow this element and supercede all previous forecast conditions.
10. Forecast Wind: 22010KT
See #5 in the UNDERSTANDING METARs section for details.
11. Forecast Visibility: 5SM
See #6 in the UNDERSTANDING METARs section for details.
12. Forecast Weather Phenomenon: -SHRA
See #7 in the UNDERSTANDING METARs section for details.
13. Forecast Sky Conditions: OVC020
See #8 in the UNDERSTANDING METARs section for details.
14. Change in Conditions: BECMG 1315
BECMG indicates “becoming” over the time interval between 1300Z
(13) and 1500Z (15). “Becoming” describes a gradual change in forecast conditions. The described conditions follow this element and
supercede previously reported like elements.
15. Wind Becoming: 20010KT
See #5 in the UNDERSTANDING METARs section for details. This
element may be omitted if no change is expected.
16. Visibility Becoming: P6SM
See #6 in the UNDERSTANDING METARs section for details. This
element may be omitted if no change is expected.
17. Weather Phenomenon Becoming: NSW
NSW indicates “No Significant Weather”. See #7 in the UNDER-
STANDING METARs section for details.
18. Sky Conditions Becoming: SKC
See #8 in the UNDERSTANDING METARs section for details. This
element may be omitted if no change is expected.
19. Change in Conditions: TEMPO 2022
TEMPO indicates “temporary” changes expected as described between
2000Z (20)and 2200Z (22). “Temporary” indicates a temporary fluctuation in conditions, usually lasting less than one hour. The described
conditions follow this element.
20. Low Level Windshear: WS015/30045KT
WS indicates “windshear” not associated with convective activity. 015
indicates the windshear is expected at 1500 feet. AGL Wind is
expected from 300° (300) at 45 knots (45KT).
21. Change in Conditions: PROB40 0407
PROB40 indicates a 40% “probability” of described conditions occurring
between 0400Z (04)and 0700Z (07). The described conditions follow
this element.
Rev 1 Oct. 2003
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UNDERSTANDING PIREPS
The following is an example of a typical PIREP with an explanation of the
elements.
13
2
KCRW UA/OV KBKW 360015-KCRW/TM 1815/FL120/TP BE99/SK IMC/
WX RA/TA M08/WV 290030/TB LGT-MDT/IC LGT RIME/RM MDT MXD
ICG DURGC KROA NWBND FL080-100 1750Z
1. Station Identifier: KCRW
This is the station identifier of the nearest weather reporting location to
the reported conditions.
2. Report Type: UA
Reports will be routine (UA) or urgent (UUA).
3. Location: OV KBKW 360015-KCRW
OV indicates the report is in relation to a VOR. KBKW is the VOR iden-
tifier, in this case Beckley VOR. 360015-KCRW indicates position as
related to the VOR. In this case, 15 miles out on the 360 degree radial.
KCRW indicates this is a leg to the Charleston, West Virginia VOR.
The next series of elements contain data that is read much like that in
METARs and TAFs. Each element starts with a 2-letter designator which
denotes the type of data with that element. The following defines the element designators:
/TM: Time as Coordinated Universal Time
/FL: Altitude as Flight Level
/TP: Aircraft Type
/SK: Sky Cover (may include cloud height and coverage)
/WX: Weather Phenomenon (can include flight visibility, precipitation
and restrictions to visibility.
/TA: Outside air temperature at altitude in degrees Celsius.
/WV: Wind (direction in degrees magnetic north and speed in knots)
/TB: Turbulence (refer to the Airman’s Information Manual)
CAT - Clear Air Turbulence
CHOP - Choppy Turbulence
OCNL - Occasional
NEG - No Turbulence
ABV - Above
BLO - Below
Rev 1 Oct. 2003
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LGT - Light - Momentarily causes slight, erratic changes in altitude and/or attitude.
MOD - Moderate - Greater intensity changes in altitude and/or
attitude, but aircraft remains in positive control at all times.
Usually causes changes in indicated airspeed.
SEV - Severe - Causes large and abrupt changes to aircraft altitude and/or attitude. Large variations in indicated airspeed and
momentary loss of control.
EXTRM - Extreme - Aircraft is violently tossed about and is nearly
impossible to control. May cause structural damage.
/IC: Icing (refer to the Airman’s Information Manual)
CLR - Clear
MX - Mixed (combination of rime and clear icing)
NEG - No Icing
ABV - Above
BLO - Below
Trace - Ice becomes perceptible. Rate of evaporation is almost
equal to the rate of accumulation. Deicing/anti-icing equipment is
not utilized unless encountered for a period of time greater than 1
hour.
LGT - Light - Rate of accumulation may be a problem if flight is
prolonged for longer than 1 hour without deicing/anti-icing equipment. Deicing/anti-icing removes and/or prevents accumulation.
MOD - Moderate - The rate of accumulation is such that even
short encounters become potentially hazardous. Use of
deicing/anti-icing equipment or diversion is necessary.
SEV - Severe - Flight diversion is necessary. Deicing/anti-icing
equipment is not effective.
/RM: Remarks (for reporting elements not included or to clarify previ-
ously reported items). Remarks can include anything. The
example translates to “moderate (MDT) mixed (MXD) icing during
climb (DURGC) from Roanoke, VA (KROA) northwestbound
(NWBND) between Flight Level 080 and 100 (FL080100) at
1750Z”.
Rev 1 Oct. 2003
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UNDERSTANDING AIRMETS
The following is an example of a typical AIRMET with an explanation of the
elements.
134
2
CHIT WA 151900 AMD
AIRMET TANGO UPDT 2 FOR TURB
5
VALID UNTIL 160100
6
AIRMET TURB...KS MO
7
FROM MCI TO STL TO SGF TO ICT TO MCI
8
9
MOD TURB BLW 100 EXPCD
CONDS IPVG AFT 160000Z
10
1. Forecast Area: CHIT
This is the station identifier of the issuing Weather Service Forecast
Office.
BOS Boston
CHI Chicago
DFW Dallas/Ft. Worth
MIA Miami
SFO San Fransisco
SLC Salt Lake City
The T denotes the reason for the AIRMET. This could be one of the
following:
S Sierra IFR Ceilings less than 1,000 feet and/or visi-
bility less than 3 miles affecting over 50%
of the area at one time or extensive mountain obscuration.
T Tango Turbulence Moderate turbulence, sustained surface
winds of 30 knots or more at the surface
or low level windshear.
Z Zulu Icing Moderate icing and/or freezing levels.
AIRMET items are considered widespread. Widespread is considered
an area of at least 3,000 square miles.
2. Report Type: WA
WA identifies an AIRMET.
3. Date and Time Issued: 151900
15 indicates the 15th day of the month. 1900 indicates UTC.
Rev 1 Oct. 2003
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4. AMD indicates an amended report. Reports can be amended due to
changing weather conditions or issuance/cancelation of a SIGMET.
COR in this field would indicate a corrected AIRMET. RTD indicates a
delayed AIRMET.
5. This line indicates that there is a second (2) update (UPDT) to this
AIRMET issued for turbulence (FOR TURB). More than one meteoro-
logical condition may be addressed as shown in the following:
FOR IFR AND MTN (mountain) OBSCN (obscuration)
FOR ICE AND FRZLVL (freezing level)
FOR STG (strong) SFC (surface) WINDS AND LLWS (low level
wind shear)
6. This updated AIRMET is valid until 0100 UTC on the 16th day (16) of
the month. An AIRMET does not contain an explicit validity start time.
7. This AIRMET forecasts turbulence (TURB) for the states of KS
(Kansas) and MO (Missouri). Geographic areas are also covered such
as CSTL WTRS (coastal waters). Other geographic abbreviations are
used as well (see Appendix A).
8. The affected area is defined by lines FROM MCI (Kansas City) TO STL
(St. Louis) TO SGF (Springfield) TO ICT (Wichita) and back TO MCI.
Areas can be defined by lines between points which are airport or
navaid identifiers.
9. Moderate (MOD) turbulence (TURB) below (BLW) 10,000 feet
expected (EXPCD).
10. Conditions (CONDS) improving (IPVG) after (AFT) the 16th day (16) of
the month 0000 UTC.
If conditions end more than one hour prior to the indicated expiration time,
an amended AIRMET will be issued stating it’s cancellation. If conditions
end within one hour of the indicated expiration time, the AIRMET will be
allowed to expire without cancellation.
Rev 1 Oct. 2003
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UNDERSTANDING SIGMETS
CHIR UWS 041430
SIGMET ROMEO 1 VALID UNTIL 041830
KY TN WV VA OH
FROM CVG TO EKN TO PSK TO VXV TO CVG
OCNL SEV TURB BTN 300 AND 360. RPRTD BY AIRCRAFT.
CONDS CONTG BYD 1830Z.
SLM/GTB
13
4
5
2
6
7
8
The following is an example of a typical SIGMET issued for turbulence with
an explanation of the elements.
1. Forecast Area: CHIR
This is the station identifier of the issuing Weather Service Forecast
Office.
BOS Boston
CHI Chicago
DFW Dallas/Ft. Worth
MIA Miami
SFO San Fransisco
SLC Salt Lake City
The R denotes report ROMEO. A new alphabetic designator is given
each time a SIGMET is issued for a new weather phenomenon. The
order of issuance is as follows:
N NOVEMBER
O OSCAR
P PAPA
Q QUEBEC
R ROMEO
U UNIFORM
V VICTOR
W WHISKEY
X XRAY
Y YANKEE
SIGMETs are issued for:
Severe icing not associated with thunderstorms
Severe or extreme turbulence or clear air turbulence (CAT)
Dust storms or sandstorms lowering visibilities to < 3 miles
Volcanic ash
2. Report Type: UWS
UWS indicates this is the first issuance of report ROMEO. Subsequent
reports for ROMEO would display WS.
Rev 1 Oct. 2003
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3. Date and Time Issued: 041430.
04 indicates the 4th day of the month. 1430 indicates UTC.
4. This line indicates that SIGMET ROMEO 1 is VALID UNTIL the 4th day
(04) of the month at 1830 UTC.
Each subsequent report issued for this same weather phenomenon
designated ROMEO would increment the number. For example,
ROMEO 2, ROMEO 3 and so on.
5. Area of coverage by state or geographic area. In addition to state
abbreviations, other area abbreviations may be seen here, such as, TX
CSTL WTRS (Texas Coastal Waters).
6. Location of weather phenomenon. Three letter designators for navaids
or airports are used to describe boundaries of coverage. If the weather
phenomenon extends across multiple forecast areas, the location is
described as if no boundaries exist.
7. Details of weather phenomenon. The example is typical of a synopsis
for turbulence:
OCNL (occasional) SEV (severe) TURB (turbulence) BTN (between)
300 (30,000 feet) AND 360 (36,000 feet). RPRTD (reported) BY AIR-
CRAFT. CONDS (conditions) CONTG (continuing) BYD (beyond
1830Z.
More typical examples of descriptors used in other SIGMET weather
phenomenon are as follows:
MOD (moderate) TO
STG (strong) UDDFS (updrafts and downdrafts)
UPDFTS (updrafts)
DWNDFTS (downdrafts)
INVOF (in vicinity of) MTNS (mountains)
BLO (below) 360
BTWN (between) FRZLVL (freezing level) AND 360
ABV (above) 360
RPRTD (reported) BY ACFT(aircraft) IN VCNTY (vicinity)
RPRTD BY SVRL (several) ACFT
8. Issuers initials.
If conditions end more than one half hour prior to the indicated expiration
time, and the report does not state that conditions will continue, a cancellation will be issued with CNCL SIGMET as the report designator. If conditions are expected to continue, a new SIGMET will be issued. If conditions
end within one half hour of the indicated expiration time, the SIGMET will be
allowed to expire without cancellation.
Rev 1 Oct. 2003
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UNDERSTANDING CONVECTIVE SIGMETS
The following is an example of a typical Convective SIGMET with an explanation of the elements.
13
2
MKCC WST 221855
CONVECTIVE SIGMET 20C
4
V ALID UNTIL 2055Z
5
ND SD
6
FROM 60W MOT-GFK-ABR-90W MOT
7
INTSFYG AREA SVR TSTMS MOVG FROM 2445. TOPS ABV FL450.
8
WIND GUSTS TO 60KT RPRTD. TORNADOES…HAIL TO 2 IN…WIND
GUSTS TO 65KT PSBL ND PTN.
1. Station Identifier: MKCC
MKC is the station identifier of the Aviation Weather Center (AWC) in
Kansas City.
The C denotes the report is for the Central portion of the continental
United States. The choices are as follows:
C Central
E East
W West
Convective SIGMETs are issued for:
Severe weather including: (a)Surface winds ≥ 50 knots,
(b) Surface hail ≥ 3/4 inch in diameter or (c) Tornadoes
Embedded thunderstorms (obscured by haze or other phenomena)
Line of thunderstorms
Thunderstorms ≥ VIP level 4 affecting ≥ 40% of an area ≥ 3000 sq. mi.
2. Report Type: WST
WST indicates this is a convective SIGMET.
3. Date and Time Issued: 221855.
22 indicates the 22nd day of the month. 1855 indicates UTC.
4. This line is the identifying number of the Convective SIGMET.
Numbering begins daily at 0000 UTC. The C denotes the Central portion of the country.
5. This line indicates that CONVECTIVE SIGMET 20C is VALID UNTIL
2055Z time. Expiration time is two hours after issuance, but Convective
Rev 1 Oct. 2003
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