METAR is a weather report used by pilots and air traffic controllers to inform them of the weather conditions at the airport they are flying from or to. In this post, we will discuss the importance of visibility in METAR and how to use METAR to your advantage.

METAR reports are very important to pilots. It tells them what kind of weather they can expect when they land or take off. It also tells them what kind of visibility they can expect. In METAR there are two types of visibility i.e horizontal visibility and vertical visibility. Horizontal visibility is the amount of distance that you can see the ground. The lower the visibility, the more obstacles on the ground. In this post, we will only discuss horizontal visibility. This is a very important factor to consider. You want to know how far you can see the ground before you decide to fly. Vertical visibility is the vertical visibility of the sky above the ground.

The horizontal visibility in METAR is measured in meters. Let’s take an example of a METAR:

METAR LUDO 090300Z 00000KT 8000 NSC 14/12 Q1012 90%=

Here in the above example, 8000 is the visibility which is read as 8000 meters or 08 Km.

If visibility is less than 05 km then the weather phenomena which is causing poor visibility should also be reported in METAR. For example:

METAR LUDO 090500Z 00000KT 4000 FU 19/12 1Q1012 60%=

Here in the above example visibility is 4000 meters due to smoke haze(FU) which is reported in METAR.

The METAR reports the prevailing visibility, which may be lower than the visibility reported. It’s not always possible to know the visibility of the sky( vertical visibility).

If visibility is 10 kilometers or more that visibility is reported as 9999. For example:

METAR LUDO 090600Z 00000KT 9999 19/12 1Q1012 60%=

If there is no significant cloud (no clouds below 8000 ft above ground level) and visibility is more than 10 km or more then instead of visibility and clouds, CAVOK is reported which means cloud and visibility are O.K. for example:

METAR LUDO 090700Z CAVOK 19/12 1Q1012 60%=

Prevailing Visibility: Horizontal Visibility should be determined by the variations of visibility in all directions around the airport. The prevailing visibility in the area is defined as “the greatest visibility value that is reached within at least half of the horizon circle or within at least half of the surface of the aerodrome. You need to know how and where visibility is measured for aviation operations. The METAR should be read with care, but it can be useful as a guide to understanding what the observer saw. The most operational significance should be indicated if the least visibility is observed in more than one direction.

Some Significant Phenomena that Cause Poor Visibility:

Various weather phenomena affect visibility. When there is dense fog visibility is reduced to a few meters. Some of the significant weather phenomena that cause poor visibility are:

Fog (FG), Rain(RA), Drizzle(Dz), Snow(SN), Dust raising wind(DRDU). Blowing wind(BLDU), Smoke haze(FU), Haze(HZ) ad many more.

Indicators +,++,-,– are also used with precipitation phenomena to show their intensity in METAR.