CAAB CPL Theory Exam key terms

The 1944 Convention on International Civil Aviation, a treaty that established ICAO and set the basic framework under which states regulate international air navigation, aircraft registration and crew licensing.

One of the numbered sets of Standards and Recommended Practices attached to the Chicago Convention, each covering a subject such as licensing, rules of the air or meteorology, which states incorporate into national regulations.

A certificate issued by the state of registry confirming that a particular aircraft conforms to its approved type design and is safe to operate, provided it is maintained in accordance with the applicable requirements.

The system of a forward-facing pitot tube and flush static ports that supplies pressure to the airspeed indicator, altimeter and vertical speed indicator, and whose blockage causes misleading readings.

The speed displayed by the airspeed indicator, derived from the difference between pitot and static pressure; because it reflects dynamic pressure it is used for handling, limiting speeds and performance tables.

The speed of the aircraft through the air mass, found by correcting indicated airspeed for air density, altitude, temperature and instrument error; used for navigation, flight planning and wind calculations.

Ice that forms in the carburettor due to fuel vaporisation and the pressure drop at the venturi, and can occur at outside temperatures well above freezing, causing rough running and progressive power loss.

A propeller whose blade angle is automatically varied by a governor to maintain a selected RPM as power or airspeed changes, giving better efficiency and reducing pilot workload.

The maximum total mass at which the aeroplane is permitted to begin its take-off run, including aircraft, fuel, crew, passengers and baggage, as set by structural and performance limits.

The point through which the whole weight of the aircraft is considered to act; it must stay within certified forward and aft limits so that stability, control and performance remain acceptable.

Pressure altitude corrected for temperature deviation from the standard atmosphere; it expresses air density and directly affects engine power, lift, and take-off and landing distances.

The fuel that must remain on board at the destination aerodrome, normally expressed as a period of holding or cruise flight, to cover delays, diversion or weather, and which is not planned for use.

A shortage of oxygen reaching the body's tissues, causing euphoria, poor judgement, headache and visual disturbance; the pilot may be unaware of it, and it worsens rapidly with increasing altitude.

A mistaken perception of the aircraft's attitude, position or motion, resulting from conflicting or absent visual cues and misleading inner-ear sensations, and a common factor in loss-of-control accidents.

A false sensation of pitching up during strong acceleration, or pitching down during deceleration, caused by linear acceleration stimulating the otolith organs; it can provoke a dangerous control input after take-off or go-around.

A state of reduced alertness and degraded performance caused by prolonged wakefulness, duty, workload or poor rest; it slows reactions and impairs judgement, and is managed through rest and duty limits.

The altimeter sub-scale setting that makes the altimeter indicate aerodrome elevation when the aircraft is on the ground there, so that in flight it shows altitude above mean sea level.

The altimeter sub-scale setting that makes the altimeter read zero when the aircraft is on the aerodrome, so that in flight it indicates height above the aerodrome or its reference point.

A routine coded observation of surface weather at an aerodrome, issued at fixed intervals, reporting wind, visibility, weather, cloud, temperature, dew point and pressure.

A coded forecast for a specified aerodrome and period, giving expected wind, visibility, significant weather and cloud, used together with other information for flight planning and fuel decisions.

The temperature to which air must be cooled at constant pressure to become saturated; a small temperature and dew-point spread indicates high humidity and likely cloud, fog or carburettor icing.

A change in wind speed or direction over a short distance, vertically or horizontally, that suddenly alters airspeed and lift; low-level shear on approach or departure is especially hazardous.

A small, intense downdraught that spreads out on reaching the ground, producing a sudden headwind followed by a tailwind; it can cause a severe loss of airspeed and performance close to the ground.

The shortest route between two points on the Earth's surface, formed by a plane passing through the Earth's centre; it appears curved on most aeronautical charts and is used for long sectors.

The angle between true north and magnetic north at a particular place, changing slowly with time and location; it must be applied when converting between true and magnetic directions.

The error of a magnetic compass caused by the aircraft's own magnetic fields and electrical equipment; it is specific to each installation and corrected using a deviation card.

The path the aircraft actually follows over the ground, expressed as a direction; wind causes it to differ from the heading, and the angular difference is known as drift.

VHF Omnidirectional Range, a ground station transmitting signals that let a suitably equipped aircraft determine its magnetic bearing from the station, used for tracking radials and airway navigation.

A notice containing information on the establishment, condition or change of any facility, service or procedure whose timely knowledge is essential to flight crews, issued by the aeronautical information service.

The rule that no non-essential conversation or activity takes place during critical phases such as taxiing, take-off, approach and landing, so that attention stays on flying and monitoring.

An operator's approved document stating which equipment may be inoperative for flight and under what conditions, allowing dispatch instead of grounding the aircraft.

The radiotelephony distress signal, spoken three times, used when an aircraft is threatened by grave and imminent danger and needs immediate assistance.

The radiotelephony urgency signal, spoken three times, used for a situation that needs attention or assistance but does not yet involve immediate danger to life.

The practice of repeating back the essential items of an ATC clearance or instruction, so that the controller can confirm the message was received and understood correctly.

To select a four-digit code on the aircraft transponder, which identifies the aircraft to ATC and appears in radar data blocks; special codes are reserved for emergencies and radio failure.

The angle between the wing chord line and the relative airflow; increasing it raises lift up to a point, after which the airflow separates and the wing stalls.

A sudden loss of lift when the critical angle of attack is exceeded and the airflow separates from the wing; it can occur at any speed, attitude or weight, and recovery needs a reduction in angle of attack.

The ratio of total lift to the aircraft's weight, expressed in g; it increases in turns and manoeuvres, raising both structural loads and the speed at which the aircraft stalls.

The part of total drag created as a by-product of producing lift, largely through wingtip vortices; it is greatest at high angles of attack and low speed, and reduced by high aspect ratio.