CAAP ATPL Knowledge Exam key terms

The speed by which a failure has occurred and the pilot must continue the takeoff, or before which the takeoff can be safely abandoned. It is chosen so that either action is possible within the runway.

The runway length at which the accelerate-stop distance equals the all-engines-operating takeoff distance to 35 ft. It is the minimum field length for a given mass, configuration and density altitude.

The runway distance needed to accelerate with all engines to V1, lose the critical engine, and bring the aeroplane to a full stop. It includes a short recognition and reaction allowance.

The gross climb path after engine failure reduced by a gradient of 0.8 percent for two-engine aeroplanes or 0.9 percent for three-engine aeroplanes. It must clear all obstacles by the required margin.

The vertical or lateral separation maintained between the net flight path and all obstacles in the takeoff, en-route or approach area. Required margins are set by the certification and operating rules.

The climb gradient actually achieved by the aeroplane, before the net reduction applied for operating rules. It is derived from the scheduled performance data for the relevant configuration and conditions.

The length of runway declared available and suitable for the ground run of an aeroplane landing. It may be shorter than the takeoff run available where a displaced threshold exists.

The length of runway declared available and suitable for the ground run of an aeroplane taking off. It is normally the physical runway length, excluding any clearway or stopway.

A defined rectangular area beyond the runway end, under control of the aerodrome authority, over which an aeroplane may make the initial climb to 35 ft. It is not usable for ground run.

A threshold located at a point on the runway other than the physical beginning. It creates extra landing distance before the threshold, but that portion is not available for landing rollout.

The forward and aft limits within which the loaded aeroplane's centre of gravity must lie. Exceeding them degrades stability or controllability and may invalidate certification.

The chord of an equivalent rectangular wing producing the same aerodynamic characteristics. CG position is often expressed as a percentage of MAC for loading calculations.

The mass of the aeroplane with all payload and crew but without usable fuel. It is a structural limit and an input to CG and performance calculations.

The mass of the aeroplane including unusable fuel, full operating fluids and standard equipment. It is the starting point for mass and balance calculations.

The maximum permissible load per unit area on a cargo or cabin floor. Exceeding it can cause structural damage even when the total mass is within limits.

The free-stream Mach number at which the local airflow somewhere on the aeroplane first reaches the speed of sound. It marks the onset of wave drag and buffet.

A nose-down pitching tendency at high subsonic Mach numbers caused by aft movement of the centre of pressure and reduced downwash on the tail. It is countered by Mach trim.

The margin between the current angle of attack or load factor and the value at which buffet onset occurs. It protects against stall or high-speed buffet in manoeuvring.

The angle between the wing chord line and the relative airflow. Lift and stall depend on it, independent of airspeed, which is why AoA sensors are used for stall warning.

The angle of attack at which the wing reaches maximum lift coefficient and stalls. It is essentially constant for a given configuration regardless of mass or speed.

A device that alerts the crew as the angle of attack approaches the stall. It typically uses a stick shaker or aural warning triggered by AoA vanes or flap/slat logic.

The system of pitot and static pressure sources feeding airspeed, altitude and vertical speed instruments. Blockages or leaks cause characteristic and sometimes misleading indications.

The reference pressure set in the altimeter so that it indicates height above a chosen datum. QNH gives elevation, QFE gives height above the aerodrome, QNE is standard pressure.

An instrument that computes airspeed from the difference between pitot and static pressure. It may display indicated, calibrated or true airspeed depending on the instrument.

The altitude above which the altimeter is set to standard pressure and flight levels are used. Below it, the altimeter is set to the local QNH.

The lowest flight level available for use above the transition altitude. It is chosen so that adequate separation exists between the transition altitude and the first usable flight level.

The rule requiring IFR flights to use flight levels consistent with magnetic track: 000 to 179 degrees use odd levels, 180 to 359 degrees use even levels. It reduces head-on conflicts.

A surface of constant pressure referenced to standard pressure 1013.25 hPa. It is used above the transition altitude so that all aircraft share a common pressure datum.

A predetermined manoeuvre keeping an aircraft within a specified airspace while awaiting further clearance. It uses standard turns, legs and timing or distance limitations.

An ATC authorisation for an aircraft to conduct an instrument approach. It includes the approach type and may include restrictions that must be read back.

A ground-based navigation aid transmitting signals that let an aircraft determine its magnetic bearing from the station. It supports radials, airway navigation and distance-measuring equipment pairing.

A transponder-based system measuring slant range from the aircraft to the ground station. Accuracy is best overhead and degrades at low altitude and long range.

A precision approach system providing lateral guidance from a localiser and vertical guidance from a glide path. It is categorised by decision height and required visibility.

The altitude at which a missed approach must be initiated if the required visual reference is not established. It is referenced to a pressure datum for precision approaches.

A satellite-based positioning system providing position, velocity and time. It supports en-route, approach and performance-based navigation, subject to integrity and augmentation.

A navigation specification stating the accuracy, integrity and continuity needed for operation in a given airspace. RNP includes on-board performance monitoring and alerting.

A circle on the Earth's surface whose plane passes through the Earth's centre. The shortest path between two points lies on a great circle, which appears curved on a Mercator chart.

A line crossing every meridian at the same angle. It is a constant true track and appears straight on a Mercator chart, but is longer than the great circle.

A cylindrical chart projection on which meridians are parallel and rhumb lines are straight. Scale increases with latitude, so great circles appear curved.

A defined atmosphere with sea-level temperature 15 C, pressure 1013.25 hPa and a lapse rate of 1.98 C per 1000 ft in the troposphere. It is the reference for performance and altimetry.

The altitude in the standard atmosphere corresponding to the actual air density. High temperature, humidity or pressure altitude increases it and degrades performance.

The altimeter setting that makes the altimeter indicate elevation above mean sea level when on the ground. It is derived from the aerodrome pressure reduced to sea level.

A change in wind speed or direction over a short distance, including downbursts and frontal shear. It can cause sudden airspeed and lift changes close to the ground.

A small, intense downdraft that spreads out on reaching the ground. It produces severe and rapidly changing wind shear, especially hazardous on approach and departure.

A condition in which body tissues receive insufficient oxygen. In aviation it may result from altitude, decompression or carbon monoxide, with insidious symptoms that impair judgement.

The period after loss of oxygen at altitude during which a person can still perform useful tasks. It shortens rapidly as cabin altitude increases.

A false perception of position or motion caused by misleading sensory inputs when visual references are poor. It is a major cause of loss of control in instrument conditions.

A false sensation of pitch caused by linear acceleration or deceleration. It can make a pilot believe the aircraft is climbing or descending when it is not.

The loss of cabin pressurisation, ranging from slow leaks to explosive decompression. Crew must don oxygen, descend and follow the emergency procedure.

The deliberate release of fuel to reduce mass before landing or to reach a safe landing mass. It is subject to specific procedures and minimum altitude restrictions.

The checklist actions for an engine fire, typically shutting off fuel, bleed air and ignition, and discharging the fire bottle. The engine is then secured and the situation assessed.

A fixed or portable system that discharges extinguishing agent into an engine, cargo or cabin zone. It is activated by crew action or automatically in some compartments.

A system that extracts compressed air from the engine compressor for cabin pressurisation, air conditioning, anti-icing and engine starting. Leaks can cause serious overheat warnings.

A document showing the distribution of mass and the resulting centre of gravity for a flight. It is checked against limits and used to compute performance data.

The distance an aircraft can fly per unit of fuel, often expressed as nautical miles per kilogram. It varies with speed, altitude and mass and underpins fuel planning.

Fuel carried in addition to trip fuel to cover unforeseen factors such as weather, routing or traffic. Its amount is set by the operator's fuel policy and rules.

The point along the route beyond which it is no longer possible to return to the departure aerodrome with the fuel remaining. It depends on fuel, wind and alternate availability.