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Keyword glossary

In aviation, you often come across familiar but sometimes very confusing abbreviations and acronyms. This list is intended to help you search for the terms in question and view their explanations.

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The ICAO defines Class A airspace as controlled airspace reserved exclusively for IFR flights (instrument flight rules). In this airspace, all flights are subject to air traffic control and a continuous two-way radio communication link is required. In addition, all aircraft in Class A airspace must receive an ATC clearance. Not all countries have class A airspace. Germany, for example, does not have this airspace. More information on airspace in our Academy.
An aircraft is "abeam" of a fixed point, point or object when it is 90 degrees to the right or left of the aircraft's flight path. Abeam indicates a general position rather than a precise point.
The runway reported as available plus stopway length
NDB transmitters are targeted with ADFs. On the ADF you set the frequency of the NDB you want to target. There are then various display options for showing the position of the aircraft in relation to the NDB.
Beacon used to recognise the location of an airfield from the air
The height of the highest point of the landing site
The Aeronautical Information Publication is a standardised reference work containing information and regulations relevant to aviation. As a rule, an Aeronautical Information Publication applies to a single country.
An AIRMET is a description of weather phenomena that occur or could occur along a flight route (forecast) and may affect the safety of aircraft. Compared to SIGMETs, AIRMETs cover less severe weather conditions: moderate turbulence and icing, persistent surface winds or widespread restricted visibility.
Air traffic control (ATC) is a system for controlling air traffic to ensure the safety, order and efficiency of flight operations. ATC personnel monitor air traffic, issue instructions to pilots and coordinate air traffic between different aircraft.
The AI (Attitude Indicator) provides an image of the aircraft's horizon position. As a rule, the display consists of an aircraft symbol and an area coloured blue (sky) and brown (ground). The pitch and bank angles can then be read off.
An aerodrome traffic zone - Aerodrome Traffic Zone (ATZ) - is an airspace defined around an aerodrome for the protection of aerodrome traffic. The entry into or departure from an aerodrome traffic zone requires authorisation (§ 22 LuftVO), i.e. aircraft that do not wish to land at an aerodrome with an ATZ must avoid the defined airspace. An ATZ usually only has very small dimensions, both horizontally and vertically. In fact, it only serves to protect traffic directly at an aerodrome. While aerodrome traffic zones have been established at some other European aerodromes, this airspace measure has only been used occasionally and for a limited time in Germany. With the establishment of a zone for Frankfurt-Egelsbach Airport in 2016, Germany now also has an ATZ.
Aviation Gasoline is the most common aviation petrol. There are different types of AVGAS which are coloured differently: AVGAS 100LL blue, AVGAS 100 green, AVGAS 80 red, AVGAS 82UL purple and AVGAS 91 brown
Airspace B according to the ICAO definition includes the following specific regulations: Flight rules: Both instrument flight rules (IFR) and visual flight rules (VFR) are permitted. However, all aircraft must be cleared by air traffic control (ATC) before they are allowed to enter this airspace. Traffic separation: IFR to IFR, IFR to VFR, VFR to VFR is staggered. IFR traffic is prioritised over VFR traffic by air traffic control. Maximum speeds: There is a speed limit of 250 knots below 10,000 feet, unless the competent authority authorises a higher speed for technical or safety reasons. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in Airspace B: Flight visibility: 8km above FL 100; 5km below FL 100 Distance to clouds: vertical 1000 ft; horizontal 1500m. Further information on airspaces in our Academy.
Airspace C according to the ICAO definition includes the following specific regulations: Flight rules: Both instrument flight rules (IFR) and visual flight rules (VFR) are permitted. However, all aircraft must be cleared by air traffic control (ATC) before they are allowed to enter this airspace. Traffic separation: IFR to IFR, IFR to VFR, (traffic information for VFR to VFR) Maximum speeds: There is a speed limit of 250 knots below 10,000 feet unless the competent authority authorises a higher speed for technical or safety reasons. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in Airspace C: Flight visibility: 8km above FL 100; 5km below FL 100 Distance to clouds: vertical 1000 ft; horizontal 1500m. Further information on airspaces in our Academy.
The CAS corresponds to the IAS, corrected for instrument or position errors. There is often a corresponding table near the airspeed indicator.
Fuse switches that jump out in the event of overload and thus protect against short circuits and fire hazards.
Constant-speed propellers allow the blades to be set at different angles. They have automatic governors to keep the preselected speed constant. Here, the power must be set via the boost pressure and speed.
Control zones - Control Zones (CTR) - are a special part of the controlled airspace. They are established exclusively around aerodromes with IFR traffic and extend 5 to 8 NM on both sides of the extended baselines of the runways, depending on the direction of the IFR approach and departure procedures. In Germany, control zones are generally classified as airspace D (abroad also as C). If the corresponding weather minima of the airspace are not given, it is only possible to fly into a control zone with special VFR.
Airspace D according to the ICAO definition includes the following specific regulations: Flight rules: Both instrument flight rules (IFR) and visual flight rules (VFR) are permitted. However, all aircraft must be cleared by air traffic control (ATC) before they are allowed to enter this airspace. Traffic separation: IFR to IFR, (traffic information for VFR) Maximum speeds: There is a speed limit of 250 knots below 10,000 feet unless the competent authority authorises a higher speed for technical or safety reasons. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in airspace D: Flight visibility: 8km above FL 100; 5km below FL 100 Distance to clouds: vertical 1000 ft; horizontal 1500m. Further information on airspaces in our Academy.
The DME can measure the distance between the aircraft and the transmitter. This is done by measuring the propagation time of electromagnetic signals. It is important that the DME on-board unit always displays the slant range in NM. So if you are exactly above the station, the device shows the flight altitude.
Airspace E according to the ICAO definition includes the following specific regulations: Flight rules: Both instrument flight rules (IFR) and visual flight rules (VFR) are permitted. No clearance is required to enter the airspace. Traffic separation: IFR to IFR; traffic information for VFR as far as possible Maximum speeds: There is a speed restriction of 250 knots below 10,000 feet. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in Airspace E: Flight visibility: 8km above FL 100; 5km below FL 100 Cloud clearance: vertical 1000 ft; horizontal 1500m. Further information on airspaces in our Academy.
You may fly into these areas at your own risk, so to speak, but it is strongly recommended that you consult FIS beforehand. Military exercises, for example, take place in these zones.
Flying into restricted areas is only permitted if this has been established in principle for the relevant zone and the specific flight has been authorised. FIS provides information on this.
Airspace F according to the ICAO definition includes the following specific regulations: Flight rules: Both instrument flight rules (IFR) and visual flight rules (VFR) are permitted. Airspace F is not controlled. Traffic separation: No separation; traffic information as far as possible Maximum speeds: There is a speed limit of 250 knots. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in airspace F: Flight visibility: 5km; distance to clouds: vertical 1000 ft; horizontal 1500m. Airspace F is not established in Germany. Further information on airspaces in our Academy.
An on-board computer is a computer on board an aircraft that performs various tasks to navigate, control and monitor the aircraft. On-board computers are mainly used in large airliners.
A flight plan is a document that describes the details of a flight. It contains information about the aircraft, the pilots, the route, the flight altitude and the planned arrival time. Under certain conditions, flight plans must be filed (e.g. for night flights or IFR flights)
Airspace G according to the ICAO definition includes the following specific regulations: Flight rules: Flights under visual flight rules (VFR) are permitted. Flights under IFR rules are only possible on defined approach and departure routes in conjunction with an RMZ. Airspace G is not controlled. Traffic separation: No separation; traffic information as far as possible Maximum speeds: There is a speed restriction of 250 knots. Weather requirements for VFR flights: Special minimum weather conditions apply for VFR flights in airspace F: Flight visibility: Flight visibility: above 3000 AMSL or 1000 AGL: 5 km in/below 3000 AMSL or 1000 AGL: 1.5 km, if IAS max. 140 kt Earth visibility Distance from clouds: above 3000 AMSL or 1000 AGL: vertical 1000 feet horizontal 1500 m in/below 3000 AMSL or 1000 AGL: clear of clouds Further information on airspace in our Academy.
GNSS is the collective term for the various satellite systems used for precise positioning and navigation. Well-known systems are: GPS from the USA, GALILEO from Europe, GLONAS from Russia and BEIDOU from China.
The HI (Heading Indicator) is used to indicate the direction of flight. It is used to facilitate the use of the compass, which is subject to many display errors.
The pilot can read the altitude on the altimeter. He must set the reference pressure on the display using a rotary knob in order to be able to read QNH, pressure altitude or QFE.
The HSI combines a VOR display with a slaved gyro, i.e. an automatically tracked heading gyro. This makes it very easy for the pilot to read the position of the aircraft in relation to the VOR.
This is the speed displayed on the airspeed indicator. As a rule, the necessary information comes from the pitot tube.
The instrument landing system is a ground-based system that helps pilots navigate to the runway during the final approach phase of the flight. It allows flight crews to perform precision approaches even at night and in poor visibility conditions.
A flight can be made either according to visual flight rules or according to instrument flight rules. In instrument flight, you fly purely according to instruments, without outward visibility. IFR can therefore also be used to fly through clouds if the aircraft is equipped accordingly.
An airspace in which air traffic control services are provided to ensure safe and orderly air traffic.
The dragonfly is integrated in the turn coordinator and usually consists of a ball that can roll in a liquid. You must always try to keep the ball in the lowest position. Only then can you fly without pushing.
A specific area of the atmosphere that is defined for air traffic.
METARs contain current weather conditions at airports, including temperature, wind speed, wind direction, visibility, cloud cover and precipitation.
The NFLs are published regularly and contain important announcements relating to flight operations, such as flight restrictions, changes in airspace or entry regulations. Unfortunately, the NFLs are not free of charge. We at Pilot-Hub always give you the most important news from the NFLs!
These are temporary amendments to the AIP that are of major importance for air traffic. The NOTAMs must be studied before every flight.
The pitot tube is used to measure the airspeed in relation to the surrounding air. Relevant here are the IAS (Indicated Airspeed), the CAS (Calibrated Air Speed) and the TAS (True Airspeed).
A primary radar emits signals that are reflected by objects. The echo that comes back is then analysed
The QFE is the current air pressure at an aerodrome in relation to the aerodrome elevation. If the QFE is set on the altimeter's secondary scale, the altimeter displays zero when the aircraft is on the runway.
The QNE is the QFE expressed as an altitude value corresponding to the ICAO standard atmosphere. The QNE is the altitude of a place that the altimeter displays on landing when the ground pressure of the ICAO standard atmosphere (1013.25 hPa) is set on the secondary scale.
The QNH is the QFE reduced to sea level (NN), whereby the aerodrome altitude and the temperature distribution of the ICAO standard atmosphere are used for the reduction. The QNH altitude is also called altitude. If the altimeter is set to QNH, the reference pressure is set so that the aerodrome altitude is displayed at the aerodrome.
A beacon is a navigational aid that emits radio signals to guide aircraft. Beacons come in different shapes and sizes, but they all use the same basic principles. Examples are NDB, VOR, DME or ILS.
A so-called Radio Mandatory Zone (RMZ) is an airspace area that may only be flown with radio contact to the associated ground radio station. These airspace areas can often be combined with Transponder Mandatory Zones (TMZ) or Aerodrome Traffic Zones (ATZ). As with a CTR, prior to entering an RMZ, registration with the responsible ground radio station with details of the aircraft type, location, flight altitude and flight intentions is required; within the RMZ, constant readiness to listen is obligatory and reporting of the departure is mandatory. Unlike the CTR, however, no clearance for entry is required in the RMZ. There is also no traffic control (exception: hazard prevention) and separation in the RMZ, but traffic information is provided. However, route clearances and altitude instructions are transmitted to IFR departures.
Standardised rules for the EU area with regard to regulations, aviation personnel, airspace, traffic rules and much more.
SIGMETs are issued to alert pilots to dangerous weather phenomena such as thunderstorms, strong turbulence and icing.
TAFs contain weather forecasts for airports for the next 6 to 24 hours.
The TAS is the true airspeed in relation to the surrounding air. It is different to IAS and CAS as the air pressure decreases with increasing altitude and therefore the measurement of the dynamic pressure at altitude provides increasingly "too low" results. As a rule of thumb: for every 1000ft of altitude, the airspeed indicator shows approx. 2% too little.
A so-called Transponder Mandatory Zone (TMZ) is an airspace area in which all aircraft must carry and use a transponder with automatic altitude transmission. These zones usually surround aerodromes that are equipped with instrument approach procedures. In accordance with NfL 2023-1-2700, it has been mandatory since 23 March 2023 for the pilot in command to switch the transponder code within the TMZ without being requested to do so and to remain on standby on the TMZ frequency. However, it is not necessary to "register" by radio, but simply to listen to the corresponding frequency. The data for this can be taken from the current ICAO chart of the corresponding airspace.
Airspaces with this suffix are restricted at certain times.
The defined route to be flown by aircraft in the vicinity of the aerodrome (take-off / landing).
The transmitter station on the ground sends out a signal that is received by the receiver (the transponder) in the aircraft and then sends a response. Currently, Mode-S transponders send an identification code, altitude and other data that can be used to analyse the aircraft, position, speed and more on the ground.
Absolute altitude, also known as "AGL" (Above Ground Level), is the vertical distance between an aircraft and the point directly below it on the ground. It is measured in feet (ft) or metres (m). The absolute altitude is important for pilots to know the height of the aircraft above the ground and to avoid collisions with obstacles such as mountains, buildings and other aircraft. The absolute altitude can be calculated using a barometric altimeter. A barometric altimeter measures the air pressure, which decreases with altitude. The altimeter is equipped with a calibrated scale that indicates the altitude above sea level. To determine the absolute altitude, the pilot must correct the pressure altitude value on the scale with the current barometric pressure (QNH) and also make a temperature correction.
The device first indicates the bank angle by means of an aeroplane symbol on the display. If the bank angle is constant, the turning speed is displayed. There are markings in the display. If you hold the wings of the displayed aircraft on the markings, you are flying a standard curve, i.e. 3° per second (2 minute curve).
An airspace in which no air traffic control services are provided and pilots are responsible for avoiding collisions.
The variometer shows the vertical speed, i.e. how many feet you climb or descend.
A flight can be made either according to visual flight rules or according to instrument flight rules. In visual flight, you fly purely by sight. For example, you are not allowed to fly through clouds.
A VOR transmitter emits two different signals. There is a reference signal and a directional signal. This enables the receiver in the aircraft to determine which direction line from the beacon (the radial) the aircraft is on. This enables more precise navigation than with the NDB.

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