METAR / TAF

METAR

The METAR is a meteorological report giving the actual weather conditions at an aerodrome at designated intervals (every 30 minutes or hour). METAR is a system of codes. Every code consists data for a meteorological parameter. Yet, some sections may not be included in the METAR report as there may be no recorded data. Let’s take a look at these sections in the example below:

1. Report type (routine weather report for aviation activities – METAR)

2. ICAO four letter aerodrome code.

3. Date/Time of observation. First two digits indicate the calender day, and the rest show the hour (Zulu or UTC time)

4. The wind group includes forecast surface winds. The surface wind is the expected wind direction (first three digits) and speed (last two or three digits if 100 knots or greater).

a) Calm winds (less than 1 knot) are encoded as 00000KT

b) If the wind is greater than 3 knots and the direction is varying by 60 degrees or more then the actual values must be recorded. A variable wind direction will be shown by VRB. VRB02KT would indicate that the wind was only 2 knots

c) For wind speeds at 4 knots or higher and the direction is varying by 60 degrees or more, then 24005KT 200V300 shows that the wind is blowing from 240 degrees at 5 knots, the wind direction is varying from 200 to 300 degrees.

d) If the wind is gusting this will be shown by a further group of figures preceded by the letter G (G15KT—- gust speed 15 knots)

5. Visibility

It is 2000 metres in the given example, but the codes may vary depending on limits.

9999 indicates that the visibility is 10 km or more.

0450 the visibility is 450 metres

0000 the visibility is less than 50 metres

1200SE the visibility to the southeast of the aerodrome is 1200 metres

1200SE 6000N the visibility to the southeast of the aerodrome is 1200 metres, 6 km to the north

Runway Visual Range (RVR) may also be included. Examples:

R18L////// RVR not measured for 18L runway

R18R/1200U RVR for runway 18R is 1200 metres upward

R36/800D RVR for runway 36 is 800 metres downward

R27/P1500 RVR for runway 27 is 1500 metres or higher

R36/M050 RVR for runway 36 is 50 metres or less

R36/500V600 RVR for runway 36 is minimum 500 metres, maximum 600 metres

6. Weather

Current weather conditions are identified with the letter codes shown below. Light snow and mist are coded in the given example.

7. Cloud

Codes for sky cloud cover amounts are:

1/8 – 2/8 = FEW (1-2 oktas),

3/8 – 4/8 = SCATTERED (SCT) (3-4 oktas),

5/8 – 6/8 – 7/8 = BROKEN (BKN) (5-7 oktas) or

8/8 = OVERCAST (OVC) (8 oktas)

In our example; BKN030 indicates broken cloud (5-7/8), and cloud height is given by the next three figures which show the altitude in hundreds of feet. 030 is 3000 ft. OVC080 = Overcast at 8000 ft

Reporting up to 10,000 ft, use 100 ft intervals, and If it is greater than 10,000 ft, use 1000 ft intervals.

CAVOK (Ceiling and visibility OK)

The visibility, cloud, and weather groups are replaved by the term CAVOK (cloud and visibility OK) when the following conditions exist simultaneously:

– Visibility is 10km or more

– No CB or TCU and no cloud below 5000 feet or Minimum Sector Altitude (MSA) (whichever is the greater)

– No significant weather at or in the vicinity of the aerodrome.

SKC (SKY Clear)

If no cloud layers are observed and two conditions (Visibility is 10km or more, No significant weather at or in the vicinity of the aerodrome) for CAVOK are not present, SKC will be used.

NSC (No Significant Cloud)

When there are no clouds of operational significance to report, no CB or TCU and CAVOK is not appropriate, the abbreviation NSC (No Significant Cloud) is used.

8. Temperature and Dew Point are both measured in Centigrade. A minus value is preceded by the letter M. In our example, M05/M06 indicates that temperature is -5°C and dew point is -6°C

9. QNH: QNH indicates sea-level pressure with the value in whole millibars value and reported as a four figure group preceded by Q.

10. Remarks

At RESN section, code RE indicates recent weather in the period since the last routine report but not at the time of observation (METAR). Code SN represents snow.

R03R4/0151 R21L1/0152 gives runway information.

Runway Condition (RDRDRERCReReRBRBR)

R: Runway

DRDR: Runway location designator according to ICAO

ER: Runway condition (Code 0919)

CR: Runway contamination/deposit (Code 0519)

eReR: Depth of deposit (Code 1079)

BRBR: Friction Coefficient or Braking Action (Code 0366)

For example:

30% of the 24Runway threshold at Ataturk Airport is covered with a 12mm layer of dry snow and breaking action is medium

DRDR : 24

ER : 4

CR : 5

eReR : 12

BRBR : 93

The CODING will be R24451293

11. In this section, the weather conditions forecasted within the two hour period after the observation time are reported. In our example, it indicates that visibility will be 4000 meters after 2 hours.

BECMG (Becoming) : expected to happen

TEMPO (Temporary)

FM (From)

TILL (Untill)

NOSIG (No Significant Change)

EXAMPLE:

Bulgaria / Burgas Airport

METAR LBBG 041600Z 12003MPS 310V290 1400 R04/P1500′ R22/P1500U +S’ BK’022 OVC050 M04/M07 Q1020 ‘OSIG 9949//91=

LBBG: Burgas Airport ICAO code.
041600Z: Date and time of observation.
12003MPS: Wind direction 120°. Wind speed 3 MPS (5.8 KT; 6.7 mph; 11 km/h). Because of the Russian influence, Bulgaria use their metric system.
290V310: wind direction from 290° to 310° variant
1400: current visibility 1,400 m (4,600 ft).
R04/P1500′ “Runway Visual Range” (RVR) 1,500 m (4,900 ft) and no significant change.
R22/P1500U: Runway22 visibility 1,500 m (4,900 ft) upward.
+S’ heavy snow
BK’022: broken sky and cloud height is 2,200 ft (670 m) (AGL). “BKN” or “OVC” indicates cloud conditions. The most important measurement here is cloud height as it is measured from the land, and in pre-flight briefings it lets us know at what point the runway at the destination airport will be visible.
OVC050: Overcast. Cloud height is 5,000 ft (1,500 m)
M04/M07: temperature −4 °C (25 °F) and dew point −7 °C (19 °F).
Q1020: Altimetre adjustment QNH. 1,020 hPa (30.12 inHg).
NOSIG: No significant change
9949//91 runway condition.
- - 99 represents all runways at the aerodrome.
  - 4 the runway is covered with snow.
  - 9 the runway is 51% – 100% closed.
  - // deposit is not measured.
  - 91 breaking action is poor. The tires will perform poorly on the runway.
CAVOK (Ceiling And Visibility Okay) and no cloud below 5000 feet or Minimum Sector Altitude. No CB or Toweing CB. Visibility is 10 km (6 mi) or greater, and there is no significant event.
= end of METAR.

TAF (Meteorology)

A Terminal Aerodrome Forecast (TAF) is a concise statement of the expected meteorological conditions at an airport during a specified period (usually from 9 to 24 hours). It is established and issued in short message format by the relevant authority based on the meteorological conditions at an airport. The period in the report usually begins at least 8 hours after its release.

The period of validity should not be less than 6 hours, no more than 30 hours. TAFs valid for less than 12 hours should be issued every 3 hours and those valid for 12 to 30 hours every 6 hours. In addition, changes can be made in the report throughout the day if necessary.

Codes and Abbreviations

FC or FT (represents TAF or Forecast) can be used together with country code in a TAF report issued for more than one aerodrome. For instance, FCUK stands for “Forecast United Kingdom”. While FC is used for short period TAFs, FT is used for longer ones.

All TAF codes can be found in AIP GEN 3-5.

The codes contain the following information and include any expected changes for one of these elements during the given period of time.

- Surface wind
- Visibility
- Weather
- Cloud

TAF Example

LTAZ 110940Z 111812 VRB02KT 9999 SCT040

- ICAO code, Nevsehir Kapadokya Airport
- Issued on the 11th day, at 09:40 UTC
- Forecast valid from the 11th at 1800Z til the 12nd at 1200Z
- Wind direction (VRB = variable), speed (2 knots)
- Runway visibility (9999 = 10 km and higher)
- Cloud (4000 ft, scattered)