Aviation glossary

Flying terms, explained

A plain-English glossary of the weather, licence and operations terms you meet around a UK flying school or club. Tap a term for the full definition, or check the live airfield weather.

CAVOKCAVOK means visibility is 10 km or more, there is no significant cloud below 5,000 ft, and no significant weather: in short, excellent flying conditions.CircuitThe circuit is the standard rectangular pattern flown around a runway for take-off and landing, used heavily in training.Civil twilightCivil twilight is the period when the sun is up to 6° below the horizon; in UK aviation, night begins 30 minutes after sunset, at the end of evening civil twilight.Flight category (VFR, MVFR, IFR, LIFR)Flight category is a colour-coded summary of conditions (VFR, MVFR, IFR or LIFR) derived from the cloud ceiling and visibility.GSTThe GST (General Skill Test) is the practical flight test a student passes with an examiner to qualify for a licence such as the PPL.Hobbs timeHobbs time is engine or airframe running time recorded by a Hobbs meter, commonly used to bill aircraft hire.IFRIFR (Instrument Flight Rules) is flying by reference to the aircraft's instruments, used in poor weather or by choice, under a defined set of rules.IMCIMC (Instrument Meteorological Conditions) is weather below the visual minima, where flight must be by reference to instruments.IR(R)The IR(R), formerly the IMC rating, is a UK rating that lets a PPL holder fly in instrument conditions within UK airspace, with defined privileges and limitations.LAPLA LAPL (Light Aircraft Pilot Licence) is a UK/EASA licence for light aircraft, requiring fewer hours than a PPL but carrying some restrictions.METARA METAR is a routine observation of the actual weather currently reported at an aerodrome.Nav exA nav ex (navigation exercise) is a cross-country training flight where the student plans and flies a route between aerodromes.NOTAMA NOTAM is a notice that alerts pilots to temporary hazards or changes, such as airspace restrictions, runway closures or unserviceable equipment.PPLA PPL (Private Pilot Licence) allows you to fly as pilot-in-command for leisure and private purposes, but not for payment.QFEQFE is the altimeter pressure setting that makes the altimeter read height above a specific datum, usually the aerodrome, so it reads zero on the ground there.QNHQNH is the altimeter pressure setting that makes the altimeter read height above mean sea level, so it shows the aerodrome's elevation when you are on the ground.SquawkA squawk is the four-digit transponder code assigned to an aircraft; the word is also used for a reported aircraft defect.Tacho timeTacho (tachometer) time is engine time scaled to rpm, typically used for maintenance scheduling rather than billing.TAFA TAF is a forecast of the expected weather at an aerodrome over a set period, usually 9, 24 or 30 hours.VFRVFR (Visual Flight Rules) is flying by visual reference to the ground and horizon, in weather at or above the visual minima.VMCVMC (Visual Meteorological Conditions) is weather good enough to fly visually, meeting the minimum visibility and distance-from-cloud requirements for VFR.Wet & dry rateA wet rate includes fuel in the aircraft hire price; a dry rate excludes fuel, which the hirer pays for separately.

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