WHAT IS METAR #TREND #SPECI #TAF #VOLMET #SIGMET #ATIS #AIRREP #METEOROLOGY FOR CPL/ATPL EXAMS

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METAR, TREND, SPECI, TAF, VOLMET, SIGMET, ATIS & AIRREP; all these are Meteorological/weather reports used by pilots to assess weather conditions; Decide on GO/NO GO criteria; to avoid bad weather en route, to find Aerodrome suitability for landing and to choose best type of approach for landing etc. So let us discuss them one by one.
2. METAR: METAR is an acronym for MET(Meteorological) A(Aerodrome)R (Report) which describes the actual weather conditions at a particular aerodrome in a coded form updated every half an hour. A sample METAR looks something like as shown on the screen. METAR contains info about name of airfield, date & time of observation, winds, visibility, current weather, cloud coverage, temp, dew point, QNH, recent weather etc. CAVOK is reported when visibility is more than 10 Km, No clouding below 5000 feet, No CB in the vicinity of aerodrome and no significant weather is reported.
METAR ends with Trend forecast which is valid for 2 hours. If there is no trend or no change in weather is expected, it ends with wording of NOSIG.
3. SPECI: SPECI is an acronym for Special Report: Format of SPECI is same as METAR. It is issued when weather conditions significantly change in the period between routine METAR observation. Sudden improvement/deterioration of weather.
4. TAF: Acronym for Terminal Aerodrome Forecast: Its forecast and not the actual weather. It is issued every 3 or 6 Hours. Coding is similar to METAR. Additionally, it contains period of validity from _ to _.
5. SIGMET: SIGMET is an acronym for Significant Met conditions either forecast or actual within a FIR. These are en-route weather conditions and not for aerodrome. These are issued whenever Thunderstorm, Heavy Hail, Tropical Cyclone, Freezing Rain, Severe Turbulence, Severe Icing, Severe mountain waves, sand/dust storm, volcanic ash cloud. Is expected or actually reported to be present.
6. VOLMET: VOL means in flight so VOLMET is met report which pilots can receive during flight on dedicated HF or VHF RT channel. You can listen to METAR/TAF/SIGMET reports for multiple aerodromes within a FIR. VOLMET is updated every hour.
7. ATIS: ATIS is acronym for Automatic Terminal information service. METAR of an aerodrome is continuously transmitted on a dedicated VHF R/T channel; so that pilots can listen to them before start up. This reduces air traffic controller’s workload for transmitting weather information to every flight. ATIS also contains information on runway in use and ATIS is updated whenever there is any change in status of any information. With every update on ATIS, an alphabetical code is attached to it for its identification. Before departure and arrival, pilot has to call out to air traffic controller that has has received the ATIS information. For example : Delhi Tower, VT-ABC, request start, Information ‘C’. That means that pilot has listened to ATIS information whose code was ‘C’.
8. AIRREP: AIREP is an acronym for Airborne report. This is the only weather/met report which is transmitted by pilots. It is mandatory for pilots to report occurrence/encounter of any of the weather conditions which falls under SIGMET report like Thunderstorm, Heavy Hail, Tropical Cyclone, Freezing Rain, Severe Turbulence, Severe Icing, Severe mountain waves, sand/dust storm, volcanic ash cloud. Any other weather information transmitted by pilots on request from controllers will also be termed as AIRREP.