Norway CPL Theory key terms

The altitude above the aerodrome elevation at which an aircraft changes its altimeter setting from the local QNH to the standard pressure setting of 1013.25 hPa when climbing. It is published for each aerodrome in Norway.

The lowest flight level available for use above the transition altitude. It varies with the local QNH and is normally given by ATC, ensuring at least 1000 ft of separation from the transition altitude.

A surface of constant atmospheric pressure related to the standard datum of 1013.25 hPa. It is expressed in hundreds of feet, so FL100 means 10,000 ft on the standard pressure setting, independent of local pressure.

The altimeter sub-scale setting that, when set on the ground at an aerodrome, makes the altimeter indicate the aerodrome elevation above mean sea level. It corrects pressure error but not temperature error.

The altimeter sub-scale setting that makes the altimeter read zero when the aircraft is on the ground at the reference point, usually aerodrome elevation. It indicates height above the aerodrome rather than altitude above sea level.

The flight level rule based on magnetic track: for tracks 000–179 degrees, use odd flight levels; for tracks 180–359 degrees, use even flight levels. It reduces the risk of head-on conflict in controlled airspace.

Weather conditions in which flight visibility, distance from cloud and cloud ceiling meet specified minima, allowing flight under visual flight rules. The minima vary with airspace class and altitude.

Meteorological conditions expressed in terms of visibility, distance from cloud and ceiling that are below the minima for visual meteorological conditions. Instrument flight rules apply and an instrument rating is normally required.

A classification (A to G) that defines the services provided, the clearance requirements, and the separation applied inside a volume of airspace. Classes A to E are controlled; class G is uncontrolled.

An authorisation for an aircraft to proceed under conditions specified by an air traffic control unit. It does not relieve the pilot in command of responsibility for terrain clearance or compliance with regulations.

The repetition by the pilot of a clearance or instruction to confirm it has been received and understood. Safety-related items such as route, level and frequency must be read back in full.

A notice distributed by means of telecommunication containing information concerning the establishment, condition or change of any aeronautical facility, service or procedure, the timely knowledge of which is essential for flight operations.

The official publication issued by a state containing aeronautical information of a lasting character essential to air navigation, including regulations, procedures, aerodrome data and airspace structure.

The point through which the total weight of the aircraft acts. Its position, expressed as a percentage of mean aerodynamic chord, must remain within the certified forward and aft limits for the flight to be legal and safe.

The chord of an imaginary rectangular wing having the same area and pitching moment characteristics as the actual wing. CG position is usually expressed as a percentage of MAC for mass and balance purposes.

The horizontal distance from the reference datum to the point where a mass acts. Multiplying each mass by its moment arm gives its moment, which is summed to locate the aircraft centre of gravity.

An arbitrary vertical plane from which all longitudinal distances used in mass and balance calculations are measured. Its position is defined by the manufacturer and is not necessarily the nose of the aircraft.

The maximum mass at which the aircraft is certified for the take-off and initial climb. It is a structural and performance limit that must not be exceeded, regardless of available runway or conditions.

The maximum mass at which the aircraft is certified to land. If the take-off mass exceeds it, fuel must be burned or jettisoned before landing so the aircraft is at or below this limit.

The take-off mass actually used for performance planning after applying all limiting factors such as runway length, obstacle clearance, climb gradient and tyre speed. It is the lower of the structural and performance-limited masses.

The runway length at which the accelerate-stop distance equals the take-off distance to 35 ft with one engine inoperative. It represents the shortest runway from which a given take-off mass is permitted.

The maximum speed at which the pilot must take the first action to stop the aircraft within the accelerate-stop distance, and the minimum speed at which the take-off can be continued after an engine failure.

The speed at which the pilot initiates rotation to the take-off attitude. It is chosen so that the aircraft reaches V2 by 35 ft above the take-off surface with the critical engine failed.

The speed to be attained by 35 ft above the take-off surface with one engine inoperative, providing the required climb gradient and controllability. It is maintained to at least 400 ft above the surface.

The pressure altitude corrected for non-standard temperature. High density altitude reduces engine power and propeller or wing lift, increasing take-off and landing distances and reducing climb performance.

The altitude indicated on an altimeter set to 1013.25 hPa. It is the reference used in aircraft performance charts and for flight levels above the transition altitude.

The speed shown on the airspeed indicator, derived from the difference between pitot and static pressure. It is affected by position and instrument error but is the primary reference for aircraft handling and limitations.

Indicated airspeed corrected for position and instrument error. At low speeds it approximates the speed the aircraft would have in incompressible flow, and it is used to enter many performance charts.

The speed of the aircraft through the airmass, equal to calibrated airspeed corrected for altitude and temperature. It is used for navigation, flight planning and calculating wind effects.

The speed of the aircraft over the ground, obtained by combining true airspeed with the wind velocity vector. It determines the time required to fly a given distance.

The direction of the aircraft's path over the ground, expressed in degrees relative to magnetic north. It is used in navigation and determines the applicable semi-circular flight level.

A vector diagram relating true airspeed and heading to wind speed and direction, producing the resulting ground speed and track. It is the basis for dead reckoning and drift calculations.

A ground-based navigation aid transmitting radio signals that allow an aircraft to determine its magnetic bearing from the station. It provides radial information for route navigation and position fixing.

A precision approach aid providing lateral guidance from a localiser and vertical guidance from a glide path, usually combined with marker beacons or DME. It permits approach to low decision heights.

A radio aid that measures the slant range from the aircraft to a ground transponder by timing signal round trips. It provides continuous distance information, often paired with VOR or ILS.

A specified altitude on a precision approach at which a missed approach must be initiated if the required visual reference has not been established. It is referenced to the altimeter with QNH set.

The procedure to be followed when an approach cannot be completed to a landing. It follows a published route and climb, and the pilot must notify ATC and comply with the clearance.

A condition in which the tissues receive insufficient oxygen. In aviation it commonly results from high altitude, reducing night vision and judgement first, and can progress to unconsciousness without reliable warning.

The period from loss of oxygen supply to the point where the pilot can no longer take protective action. It shortens rapidly with increasing altitude and is a key reason for supplemental oxygen.

Rapid or deep breathing that lowers carbon dioxide in the blood, causing dizziness, tingling and confusion. Its symptoms resemble hypoxia, so treatment begins with controlling breathing and checking oxygen supply.

A false perception of the aircraft's position or motion relative to the earth, often caused by conflicting vestibular and visual cues in cloud or darkness. Trusting flight instruments is the primary defence.

A false sensation of pitch caused by linear acceleration or deceleration, such as the impression of pitching up during take-off acceleration. It can lead a pilot to push the nose down incorrectly.

The angle between the wing chord line and the relative airflow. Lift increases with angle of attack up to the critical angle, beyond which the wing stalls regardless of airspeed.

The angle of attack at which the airflow separates from the wing and lift decreases abruptly. It is a fixed value for a given configuration and is reached at any speed if the angle is exceeded.

Drag caused by the generation of lift, resulting from the rearward tilt of the lift vector and wingtip vortices. It decreases with increasing airspeed and increases with aircraft weight.

The ratio of the lift produced to the aircraft weight. It increases in turns and manoeuvres, raising the stall speed and structural loading on the airframe.

A condition in which the wing exceeds its critical angle of attack and lift decreases, accompanied by buffet and loss of control effectiveness. Recovery requires reducing the angle of attack.

A routine aerodrome weather report giving wind, visibility, weather, cloud, temperature, dew point and pressure. It is issued at fixed intervals and is essential for departure and arrival planning.

A terminal aerodrome forecast predicting conditions at an aerodrome over a stated period. It includes expected wind, visibility, weather and cloud, and is used to plan alternates and fuel.

The accumulation of ice on aircraft surfaces when flying through supercooled water droplets. It reduces lift, increases drag and weight, and can impair control surfaces and engine operation.

The lowest altitude in the atmosphere at which the air temperature is 0 degrees Celsius. It indicates where icing is likely and is a key item in weather briefing for flight planning.

A generator of alternating current driven by the engine, supplying electrical power in flight and recharging the battery. Failure requires load shedding and may limit flight under instrument conditions.

A common electrical conductor that distributes power from sources such as the battery and alternator to the various circuits and consumers on the aircraft.

A protective device that opens an electrical circuit automatically when current exceeds a rated value, and can usually be reset. It protects wiring from overheating and fire.

The system of pressure sources and lines that supplies total pressure from the pitot tube and static pressure from the static ports to the airspeed indicator, altimeter and vertical speed indicator.

The property of a spinning gyroscope that keeps its axis fixed in space unless acted on by an external force. It is the principle behind the attitude indicator and directional gyro.

The apparent tilting of a spinning gyroscope's axis when a force is applied, occurring 90 degrees later in the direction of rotation. It is used in rate gyros and turn indicators.