Mauritius DCA ATPL Theory key terms

The 1944 international treaty that established the legal framework for civil aviation, creating ICAO and setting out the rights and obligations of contracting states regarding airspace, aircraft registration and safety standards.

One of the numbered technical standards and recommended practices attached to the Chicago Convention, covering subjects such as personnel licensing, rules of the air, meteorology and aircraft operations, which contracting states implement nationally.

A document issued by a state confirming that a specific aircraft conforms to an approved type design and is considered safe for flight when maintained in accordance with the applicable requirements.

A mandatory instruction issued by the state of design and adopted by the state of registry requiring inspection, modification or limitation on an aircraft or component to correct an unsafe condition.

The set of commercial aviation rights granted between states, ranging from overflight and technical stops through to carrying traffic between two foreign states or within a foreign state's domestic market.

The carriage of passengers, cargo or mail between two points within the same state by an aircraft registered in another state, normally restricted or prohibited unless specifically authorised.

A notice distributed by an aeronautical information service containing time-critical information about hazards, changes or restrictions at an aerodrome, facility or airspace that pilots need before flight.

The Aeronautical Information Publication: a state-issued document containing lasting aeronautical information essential to air navigation, including aerodromes, airspace, procedures and regulatory differences from ICAO standards.

A four-digit octal code entered into the aircraft transponder so that secondary surveillance radar and air traffic control can identify and track that specific flight.

A ground radar system that interrogates aircraft transponders and uses the replies to determine identity, and with modern systems altitude, in addition to range and bearing.

Traffic Collision Avoidance System: airborne equipment that interrogates nearby transponders, displays surrounding traffic and issues traffic advisories and resolution advisories to reduce collision risk.

A TCAS instruction telling the flight crew to adjust vertical speed, or maintain it, in order to increase separation from a conflicting aircraft; it must be followed promptly unless it conflicts with safety.

VHF Omnidirectional Range: a ground navigation beacon transmitting signals that allow an aircraft receiver to determine the magnetic bearing of the aircraft from the station.

Distance Measuring Equipment: a transponder-based system that measures the slant range between the aircraft and a ground station by timing the round trip of interrogating pulses.

Instrument Landing System: a precision approach aid providing lateral guidance from a localiser and vertical guidance from a glide path, together with range information from marker beacons or DME.

The vertical guidance beam of an ILS, typically set at about three degrees, which the aircraft follows on final approach to reach the runway touchdown zone.

Global Navigation Satellite System: satellite constellations providing position, velocity and time signals used for en-route navigation, area navigation and non-precision or augmented approaches.

Receiver Autonomous Integrity Monitoring: a function in GNSS receivers that checks the consistency of satellite signals and warns the crew when navigation accuracy cannot be relied upon.

The ratio of true airspeed to the local speed of sound in the surrounding air; it governs compressibility effects and is the controlling speed for high-altitude and swept-wing limitations.

The free-stream Mach number at which airflow somewhere on the airframe first reaches the local speed of sound, producing shock waves and the onset of drag rise.

A nose-down pitching tendency at high Mach number caused by aft movement of the centre of pressure and shock-induced flow separation over the wing, requiring corrective elevator input.

The narrow speed band at high altitude between the low-speed stall boundary and the high-speed Mach buffet boundary, where the margin for manoeuvre becomes very small.

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.

The angle of attack at which the wing reaches maximum lift coefficient; any further increase causes separation of airflow and a stall regardless of speed or attitude.

Drag that arises from the generation of lift, caused by rearward inclination of the lift vector and wingtip vortices; it is greatest at low speed and high angle of attack.

The point through which the total weight of the aircraft acts; its position must remain within approved forward and aft limits for controllability and stability in all phases of flight.

The mass of the aircraft with all operating equipment, unusable fuel and full oil but excluding crew, passengers, usable fuel and payload; the starting point for mass and balance calculations.

The mass of the aircraft and its contents excluding usable fuel. It must not exceed the maximum zero fuel mass and is used to check structural and loading limits before fuel is added.

The horizontal distance from the reference datum to a load's centre of gravity; multiplying each load by its arm gives the moment used to locate the aircraft centre of gravity.

The declared length of runway plus any clearway, measured from the start of the take-off run, within which an aircraft must be able to reach a defined height with the critical engine failed.

The runway length at which the accelerate-stop distance equals the take-off distance to 35 feet with one engine failed, giving the most limiting combination of V1 and field length.

The take-off decision speed: the speed at or above which a failure before rotation should be handled by continuing the take-off, and below which the take-off should be abandoned.

The take-off safety speed at which the aircraft is assumed to be controllable after an engine failure and which must be attained by 35 feet above the runway end.

Calibrated airspeed corrected for compressibility effects at the aircraft's altitude; it relates directly to dynamic pressure and therefore to structural and aerodynamic loads.

The actual speed of the aircraft through the surrounding air mass, obtained by correcting equivalent airspeed for air density at the flight level; used for flight planning and navigation.

The speed of the aircraft relative to the ground, being the vector sum of true airspeed and the wind; it determines time and fuel required between navigation points.

A vector diagram combining true heading and true airspeed with the wind vector to derive track, groundspeed and the drift or heading correction required.

The angular difference between the aircraft's heading and its actual track over the ground, caused by the crosswind component of the wind.

A condition in which the body's tissues receive insufficient oxygen, causing impaired judgement, euphoria and loss of consciousness; it is insidious and the affected person may not recognise the symptoms.

The period after loss of cabin pressurisation during which a person can still take effective corrective action before hypoxia renders them incapable.

A false perception of the aircraft's position or motion relative to the earth, typically arising when visual references are lost and the pilot misinterprets vestibular sensations instead of trusting instruments.

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

International Standard Atmosphere: a reference model of pressure, temperature and density against altitude, used to calibrate instruments and to compare aircraft performance under standard conditions.

The altitude indicated by an altimeter set to the standard sea-level pressure of 1013.25 hPa; used for flight levels and for performance calculations.

The pressure altitude corrected for non-standard temperature; it represents the altitude at which the air density would produce the same aircraft and engine performance.

The altimeter subscale setting that, when entered on the ground, causes the altimeter to indicate aerodrome elevation; used for altitude references below the transition altitude.

The altitude above which pilots set the standard pressure setting and refer to flight levels, and below which the local QNH is used for altitude.

The aircraft system supplying total pressure from the pitot tube and static pressure from the static ports to the airspeed indicator, altimeter and vertical speed indicator.

Obstruction of the pitot tube, often by ice or insects, which traps pressure in the airspeed indicator and causes the reading to behave like an altimeter, increasing in a climb and decreasing in a descent.

The property of a spinning gyroscope that keeps its spin axis fixed in space unless acted on by an external torque, forming the basis of the attitude indicator and heading indicator.

The tendency of a spinning gyroscope's spin axis to move at right angles to an applied force, used in rate gyros such as the turn indicator.

Compressed air taken from the engine compressor and used for cabin pressurisation, air conditioning, anti-icing and engine starting; its extraction reduces available engine thrust.

The equivalent altitude corresponding to the pressure maintained inside a pressurised cabin; it is kept below a maximum certified value to protect occupants from hypoxia.

Equipment that prevents ice formation on critical surfaces such as wing leading edges, engine intakes and pitot heads, using hot bleed air, electrical heating or chemical fluid.

The aircraft system, typically using halon or an inert agent discharged into an engine nacelle, cargo hold or APU compartment, that extinguishes or contains a fire in flight.

A continuous sensing element installed in an engine or compartment that responds to overheating or flame and triggers a cockpit warning, with loop failure itself annunciated.

A structured list of actions for handling abnormal or emergency situations, read and actioned by the crew in sequence to ensure critical items are not omitted under stress.

The cognitive process of selecting a course of action among alternatives, in aviation formalised in models such as FORDEC or DECIDE to manage risk under time pressure.

A pilot's accurate perception and understanding of what is happening in and around the aircraft, including its state, the environment and the likely future evolution of events.