Airport weather interpretation METAR
May 21, 2017
Often in life we are faced with bad weather conditions. In aviation, weather conditions for takeoff, flight and landing are extremely important. Before the flight, the pilot of an aircraft always receives the weather conditions at the airport of departure and arrival, as well as on the route of the aircraft. And if these weather conditions are not satisfactory, then the pilot has every right to cancel the flight or change the departure time to when the weather forecast shows improvement.
Of course, to ensure flights, there is not enough information like the one that everyone is used to hearing from TV: “it will be cloudy tomorrow, it may rain.” Aviation meteorological forecasts and observations include a number of specific parameters, in addition, the requirements for the accuracy of these data are very high.
Information about the actual weather is encoded in a special international format called METAR. It is this code that will be discussed in this article. Any self-respecting aviation specialist, be it a pilot, dispatcher or ground staff, should not only understand this code, but also be able to instantly assess the weather conditions just by glancing at METAR.
So, the METAR report is data on the actual weather at the aerodrome and a short-term forecast for two hours from the moment of observation. The summary is issued every half an hour, but it gets into international databases with a slight delay, usually 10 minutes.
To search for the METAR of an aerodrome of interest, we recommend using the US government website aviationweather.gov, as it provides direct access to the international database.
In general, the code is quite primitive, it is enough to know about two dozen of the most common abbreviations, and the location of one or another parameter in the code, this will allow you to understand 90 percent of all reports. Let's take a real METAR summary as an example.
UAAA 221700Z 16002MPS 0500 R23R/1800D R23L/1400N FZFG FU SCT200 M11/M13 Q1028 R88/CLRD65 NOSIG
UAAA is the designation of the ICAO airfield, in this case Almaty, of course, it is impossible to know the codes of all airfields, they can be easily found on the Internet.
221700Z – date of observation (22nd of the current month) and time (17.00Z – GMT).
16002MPS - The direction of the meteorological wind (i.e. where the wind is blowing from) is 160 degrees and the speed is 2 meters per second.
0500 - meteorological visibility - 500 meters.
R23R/1800D R23L/1400N - runway visual range, in this case, on runway 23R, visibility is 1800 meters, and on runway 23L 1400 meters, D and N mean the trend in visibility over the last 10 minutes, D - Down, i.e. visibility worsened, N - no change
FZFG FU - weather phenomena. Freezing Fog Fume - supercooled fog, smoke
SCT200 - The amount of cloudiness and its lower limit: Scattered - scattered, 200 - height in hundreds of feet, i.e. 20,000 ft.
M11/M13 is temperature/dew point, M means minus.
Q1028 - airfield QNH pressure, 1028 hectopascals.
R88 / CLRD65 - runway state group, R88 - all runways of the aerodrome, CLRD - cleared (cleared), 65 - friction coefficient 0.65.
NOSIG - forecast for 2 hours from the time of observation, NOSIG - No Significant Change (no significant changes)
As you can see, there is nothing difficult in deciphering METAR, below is detailed information with all the abbreviations.
Deciphering the meteorological code METAR.
METAR is a regular report on the actual weather at the aerodrome.
Examples: UUE; LKPR; EHHK
СССС is the international four-letter designation of the aerodrome.
Airport indices are given in the collection ICAO Doc 7910 - “Indicators (indices) of location”.
Examples: 101230Z; 270030Z; 010100Z
YYGGggZ: YY - date, GG - hours, gg - minutes, Z - UTC - universal coordinated time.
Examples: 24022KT; 23009G15MPS; 17003MPS 130V220; 00000MPS
dddff (Gfmfm) (dndndnVdxdxdx) - wind at the surface of the earth
(for the 10-minute period preceding the observation period).
ddd is the average meteorological wind direction (true).
ff is the average wind speed.
Gfmfm is the maximum wind or gust speed. G-GUST - impulse.
Transmitted if the maximum speed exceeded the average speed by 5 m/s (10 knots, 20 km/h) or more.
MPS - METRES PER SECOND - meters per second.
KT - KNOTS - knots.
KMH - KILOMETRES PER HOUR - kilometers per hour.
dndndnVdxdxdx - if the wind changed sharply (at least 60 degrees at an average speed of at least 2 m/s), the report includes a group in which dndndn and dxdxdx are two extreme wind directions between which changes occurred.
V is the letter designator of the group.
00000 - calm (CALM).
VRB - VARIABLE - unstable wind.
This designation is used instead of the direction if: the average wind speed is not more than 2 m/s
(3 knots, 6 km/h) or it is not possible to determine the average wind direction.
Examples: 1400 1200NE; 9999; 0350 0150W
VVVV (Dv) (VxVxVxVxDv) — horizontal visibility near the earth's surface (meteorological visibility range).
VVVV is the visibility value in meters.
9999 - visibility over 10 km.
If visibility is
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