BendixKing KAC 503 User Manual

Understanding Aviation

Weather Reports

WARNING

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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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Rev 1 Oct. 2003

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

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

Rev 1 Oct. 2003

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

UNDERSTANDING TAFS

Refer to the numbers on the following diagram to find the appropriate descriptions.

1345

TAF KPIT 091730Z 091818 22020KT 3SM -SHRA BKN020

FM2030 30015G25KT 3SM SHRA OVC015 WS015/30045KT

TEMPO 2022 1/2SM TSRA OVC008CB

FM0100 27008KT 5SM -SHRA BKN020 OVC040 PROB40 0407 00000KT 1SM -RA BR

FM1000 22010KT 5SM -SHRA OVC020 BECMG 1315 20010KT

P6SM NSW SKC

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

Rev 1 Oct. 2003

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

UNDERSTANDING PIREPS

The following is an example of a typical PIREP with an explanation of the elements.

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

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

UNDERSTANDING AIRMETS

The following is an example of a typical AIRMET with an explanation of the elements.

134

CHIT WA 151900 AMD AIRMET TANGO UPDT 2 FOR TURB

VALID UNTIL 160100

AIRMET TURB...KS MO

FROM MCI TO STL TO SGF TO ICT TO MCI

8 9

MOD TURB BLW 100 EXPCD CONDS IPVG AFT 160000Z

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

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

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

4 5

6 7

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

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

UNDERSTANDING CONVECTIVE SIGMETS

The following is an example of a typical Convective SIGMET with an explanation of the elements.

MKCC WST 221855 CONVECTIVE SIGMET 20C

V ALID UNTIL 2055Z

ND SD

FROM 60W MOT-GFK-ABR-90W MOT

INTSFYG AREA SVR TSTMS MOVG FROM 2445. TOPS ABV FL450.

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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