action de freinage
Pilot- or airport-reported assessment of runway surface stopping quality: good/medium/poor/nil.
View termCategories
Meteorology
Browse Meteorology terms for pilots, air traffic controllers, cabin crew and aviation learners.
Languages
Altitude de pression
The altitude indicated by a barometric altimeter set to the standard pressure setting of 1013.25 hPa or 29.92 inHg. Used as a reference for aircraft performance calculations.
View termaltocumulus castellanus
Medium-level turreted cloud with rising towers indicating mid‑level instability, possible precursor to thunderstorms.
View termanti‑givrage
Application of fluid to prevent ice formation during ground operations or flight.
View termAtmosphère standard internationale
A model of the atmosphere based on standard average conditions at sea level, used for calibrating instruments and performance calculations. Defined by ICAO: 15°C, 1013.25 hPa, and lapse rate of 2°C per 1000 ft.
View termBarbule de Vent
A graphic symbol used on meteorological charts to represent wind speed and direction at a specific location and altitude, typically shown as a shaft with barbs and pennants.
View termbase des nuages
Lowest altitude of the visible cloud layer, reported as base of scattered, broken, overcast.
View termBasse Pression
An area of the atmosphere where the pressure is lower than that of the surrounding region, often associated with unsettled weather, precipitation, and potential turbulence.
View termCarte de Prévision
A weather chart produced by meteorological authorities that forecasts the expected positions of pressure systems, fronts, and significant weather for a specified future time.
View termCarte de Temps Significatif
A meteorological chart that displays forecasted significant weather phenomena, including turbulence, icing, and cumulonimbus clouds, relevant for flight safety at specific flight levels.
View termCarte d’Altitude
A meteorological chart depicting wind, temperature, and pressure patterns at specified altitudes above the earth’s surface, used to forecast enroute weather conditions for aviation operations.
View termCarte d’Analyse de Surface
A weather chart depicting current meteorological features such as pressure systems, fronts, and precipitation areas at the Earth's surface; essential for flight planning and enroute weather briefing.
View termcisaillement du vent
A sudden change in wind speed and/or direction over a short distance, hazardous during takeoff and landing.
View termcisaillement du vent bas niveau
Wind shear occurring below 2 000 ft AGL, especially hazardous during takeoff and landing phases.
View termcourant‑jet
A narrow, fast-flowing air current in the upper atmosphere, typically between 20 000 and 50 000 ft, affecting cruise performance.
View termcumulonimbus encastré
Cumulonimbus cloud obscured within other cloud layers, not visually identifiable, but with severe turbulence and precipitation.
View termcumulus bourgeonnant
Large cumulus cloud with strong vertical development, indicating convective activity, but not yet cumulonimbus.
View termDiagramme Skew-T Log-P
A thermodynamic diagram used in meteorology to plot atmospheric soundings, displaying temperature, dew point, and wind profiles with altitude to assess atmospheric stability and forecast weather hazards.
View termdurée d’action
Estimated time fluid will prevent ice before need for re‑application.
View termdécapage du givre
Removal of existing frost, ice or snow from aircraft surfaces before flight.
View termfriction piste
Measurement of friction coefficient between tires and runway; indicates braking performance.
View termFront Chaud
A boundary where a warm air mass advances and rises over a retreating cold air mass, usually resulting in steady precipitation and lower clouds along the front.
View termFront Froid
A weather front where a cold air mass advances and displaces a warmer air mass, often producing showers, thunderstorms, and abrupt changes in wind and temperature.
View termFront Occlus
A composite weather front formed during the process of cyclogenesis when a cold front overtakes a warm front, leading to complex weather patterns including precipitation and changes in wind direction.
View termGivrage
The accumulation of ice on aircraft surfaces due to supercooled water droplets, which can affect aerodynamics and instrument performance.
View termGivrage Blanc
The formation of rough, milky, opaque ice due to rapid freezing of supercooled water droplets on aircraft surfaces.
View termgivrage mixte
Presence of both rime and clear ice types on aircraft surfaces.
View termGivrage Transparent
The formation of smooth, transparent ice on aircraft surfaces, resulting from slow freezing of large supercooled water droplets.
View termgrosse goutte surfondue
Liquid droplets below freezing point that can remain liquid until striking an object.
View termHaute Pression
An area of the atmosphere where the pressure is higher than that of the surrounding region, often associated with stable weather, clear skies, and reduced turbulence.
View termInformation météorologique significative
A weather advisory issued by a Meteorological Watch Office concerning significant en‑route weather hazards affecting flight safety.
View termInformation météorologique significative cendres volcaniques
A SIGMET concerning volcanic ash clouds that may affect en‑route flight safety.
View termInversion de température
A meteorological condition where temperature increases with altitude instead of decreasing, which can trap pollutants and affect aircraft climb performance.
View termMessage de Vent et Température en Altitude
A meteorological report providing forecasted wind direction, wind speed, and temperature at specific altitudes above mean sea level, used for flight planning and fuel calculations.
View termmicro-rafale
A small, intense downdraft producing damaging winds near the ground, hazardous to aircraft during takeoff or landing.
View termNiveau de congélation
The lowest altitude in the atmosphere at which the air temperature drops to 0°C (32°F), marking the boundary where liquid water can freeze.
View termNiveau de Température Significatif
A specific altitude or flight level at which temperature changes are forecast to be significant for flight operations, affecting aircraft performance, icing risk, or fuel management.
View termnuage cumulonimbus
Towering vertical cloud with significant turbulence, precipitation, and lightning potential.
View termNuage de Rotor
A turbulent, low-level cloud formation found downwind of mountain ranges, forming in the rotor zone beneath and near mountain waves; indicative of severe turbulence and hazardous for aviation.
View termNuage Lenticulaire Stationnaire
A smooth, lens-shaped cloud that forms at high altitudes in the crest of mountain waves; often stationary, and indicative of significant atmospheric turbulence downwind of mountain ranges.
View termOnde orographique
A standing atmospheric wave created when stable air flows over a mountain or ridge, often causing turbulence and rotor clouds.
View termorage
Convective weather event with thunder, lightning, precipitation and possible severe turbulence.
View termpiste contaminée
Runway with >25% surface covered by standing water ≥3 mm, slush, snow, ice.
View termplafond
Height above ground at which an unbroken or overcast cloud layer exists.
View termPression Barométrique
The atmospheric pressure as measured by a barometer, used to determine altimeter settings and to ensure altitude accuracy during flight operations.
View termPrévision de tendance à court terme (TREND)
A TREND appended to a METAR or SPECI giving expected significant changes in surface wind, visibility, weather or cloud over the next two hours.
View termPrévision de zone pour vols à basse altitude (GAMET)
A GAMET area forecast describing significant weather below FL100 (or FL150 over mountainous terrain) within a FIR, supporting VFR and low-level IFR planning.
View termPrévision d’aérodrome terminale
A concise statement of the expected meteorological conditions at an aerodrome for a specified period.
View termrafale
A sudden, brief increase in wind speed, typically varying with rapid fluctuations.
View termrapport de conditions de piste
Aerodrome-issued report of runway surface condition using RCAM and RWYCC.
View termRapport météorologique d’aérodrome
Routine coded weather observation for a specific aerodrome at a specific time.
View termRapport spécial d’aérodrome
An unscheduled aerodrome weather report issued when significant meteorological changes occur between routine METARs.
View termRéglage altimétrique utilisant la pression standard
An altimeter setting based on the standard pressure of 1013.25 hPa or 29.92 inHg, used above the transition altitude. Known as QNE in ICAO terminology.
View termRéglage altimétrique à l'altitude de l'aérodrome
The altimeter setting that displays the elevation of the aerodrome as the altitude on the altimeter when on the ground. Referred to as QFE in ICAO terminology.
View termRéglage altimétrique à la pression au niveau de la mer
The altimeter setting that corresponds to the atmospheric pressure at mean sea level. Referred to as QNH in ICAO phraseology.
View termRéglage de l’Altimètre
The current local atmospheric pressure value set in an aircraft’s altimeter to ensure correct indication of altitude above mean sea level, typically given in hectopascals (hPa) or inches of mercury (inHg).
View termService automatique d'information terminale (ATIS)
A continuous broadcast of recorded aerodrome information, including weather, runways and NOTAMs, provided to reduce controller-pilot communication workload.
View termSIGMET cyclone tropical – Information météorologique significative
A SIGMET issued for a tropical cyclone within or approaching an FIR, including observed or forecast TC position, extent of associated cumulonimbus clouds, movement and intensity.
View termSnow NOTAM
Special NOTAM issued when snow, ice or slush significantly affects aerodrome movement areas.
View termSondage Atmosphérique
A vertical profile of the atmosphere obtained by balloon or remote sensing, recording temperature, humidity, wind, and pressure at various altitudes for weather analysis and flight planning.
View termsquale
Sudden increase in wind speed of at least 15 knots, sustained for at least one minute.
View termSystème automatisé d'observation météorologique (AWOS)
An unattended station that continuously measures and broadcasts real-time surface weather elements to pilots and ATC on a discrete frequency.
View termtropopause
The boundary layer between troposphere and stratosphere, marked by a temperature inversion, affecting flight levels and turbulence potential.
View termturbulence
Irregular atmospheric motion caused by eddies and vertical currents, affecting aircraft stability, comfort, and sometimes control.
View termturbulence en air clair
Turbulence occurring in clear skies, typically at high altitudes near the jet stream, with no visible weather phenomena.
View termturbulence modérée
Turbulence that causes changes in altitude and/or attitude but aircraft remains in control; occupants may feel strain against seat belts.
View termturbulence sévère
Turbulence that causes large, abrupt changes in altitude and/or attitude. Aircraft may be momentarily out of control. Occupants are forced violently against seat belts.
View termvisibilité
Greatest distance at which prominent objects are visible and identifiable by day.
View termvisibilité de piste
Distance over which runway markings or lights are visible from centreline on approach.
View termvisibilité dominante
Greatest visibility value equaled or exceeded for at least half the horizon.
View termÉcart à l’atmosphère standard internationale
The difference between the actual atmospheric temperature and the standard temperature defined by the International Standard Atmosphere at a given altitude.
View term