Mozambique IACM Commercial Pilot (CPL-A) key terms

A defined volume of airspace around an aerodrome, established to protect aircraft operating in the traffic circuit. Entry normally requires radio contact with the aerodrome authority and compliance with its instructions.

A document confirming that an individual aircraft conforms to its approved type design and is considered safe to operate. It remains valid only while maintenance, modifications and operating limitations are complied with.

Airspace of defined dimensions within which air traffic control service is provided to flights in accordance with the applicable rules. Classes differ in whether clearance is required and whether VFR is permitted.

An authorisation issued by an air traffic controller for an aircraft to proceed under specified conditions. It is not an instruction to act if safety is in doubt, and it must be read back when required.

The condition of an aircraft, its components and equipment being fit for safe flight within approved limitations. It is maintained through design approval, inspection, maintenance and compliance with mandatory instructions.

A certification, signed by authorised maintenance personnel, stating that specified maintenance has been completed and the aircraft or component is fit for return to service. It is evidence that required work was performed.

The permitted forward and aft limits of an aircraft's centre of gravity for a given configuration and weight. Exceeding them can degrade stability, control and performance, so loading must be checked before flight.

The calculation of total aircraft mass and the position of its centre of gravity, based on the masses and arms of loaded items. It ensures the aircraft remains within certified weight and balance limits.

The greatest mass at which an aircraft is certified to begin take-off, accounting for structure, performance and climb requirements. It may be further limited on a given day by runway, obstacle or temperature conditions.

The altitude corresponding to a given air density in the standard atmosphere. High temperature, high elevation or high humidity raises it, reducing engine power, propeller thrust and lift, and lengthening take-off and landing distances.

The altitude indicated when the altimeter subscale is set to standard pressure, 1013.25 hPa. It is used for flight levels and performance calculations rather than for terrain clearance near the ground.

The altitude at or below which an aircraft's altimeter is set to local pressure and above which it is set to standard pressure. It separates altitudes used near the ground from flight levels used in cruise.

A surface of constant pressure shown on an altimeter set to standard pressure, expressed in hundreds of feet. Flight levels provide a common vertical reference for aircraft cruising above the transition altitude.

A condition in which body tissues receive insufficient oxygen. In flight it can arise from high altitude without supplementary oxygen, and it impairs judgement and vision before the person becomes aware of the danger.

The period after loss of adequate oxygen supply during which a person can still take corrective action. It shortens rapidly as altitude increases and is reduced by cold, fatigue and physical exertion.

A mistaken perception of the aircraft's attitude or motion caused by misleading sensory inputs, especially without visual reference to the horizon. The pilot must rely on instruments rather than sensations.

A false sensation of banking that can occur after a prolonged gentle turn followed by a return to level flight. The pilot may wrongly believe the aircraft is banked the other way and apply further bank.

Abnormally rapid or deep breathing that lowers carbon dioxide in the blood, causing dizziness, tingling and confusion. Its symptoms resemble hypoxia, but the treatment is to slow the breathing rate.

A reference model of the atmosphere with defined sea-level pressure, temperature and lapse rates. It allows altimeters and performance data to be compared under consistent assumed conditions.

The altimeter subscale setting that makes the instrument indicate elevation above mean sea level when the aircraft is on the ground. It is used for terrain clearance and for altitudes below the transition altitude.

The altimeter subscale setting that makes the instrument read zero when the aircraft is on the ground at the reference point. It is used in some aerodrome circuits to show height above the aerodrome.

A layer of the atmosphere in which temperature increases with height instead of decreasing. It suppresses vertical mixing, traps haze and pollutants beneath it, and can produce low-level wind shear.

The accumulation of ice on aircraft surfaces, caused mainly by flight through supercooled water droplets. It adds weight, disrupts airflow and can reduce lift, increase drag and impair engine and instrument operation.

Ice formation inside a carburettor caused by cooling of the fuel-air mixture, often in mild humid conditions. It can cause rough running or engine stoppage even when outside air temperature is well above freezing.

A change in wind speed or direction over a short distance, vertically or horizontally. Low-level shear on approach or departure can cause sudden airspeed and lift changes and may be dangerous near the ground.

A small, intense downdraught that spreads outwards on reaching the ground, producing a strong localised outflow. Aircraft encounter a headwind, then downdraught, then tailwind, with severe performance loss.

The angular difference between true north and magnetic north at a given place, changing slowly over time. It must be applied when converting between true and magnetic directions on charts and in navigation.

The error of a magnetic compass caused by the aircraft's own magnetic fields and electrical equipment. It is specific to each aircraft and heading, and is recorded on a compass correction card.

The direction in which the aircraft's longitudinal axis is pointed, measured relative to a chosen reference such as magnetic or true north. It differs from track when the aircraft drifts in wind.

The actual path of an aircraft over the ground, expressed as a direction. It results from the combination of heading and wind, and differs from heading whenever drift is present.

The displacement of an aircraft from its intended path caused by wind, measured as the angle between heading and track. It is corrected by applying a wind correction angle.

The angle between the wing chord line and the relative airflow. Increasing it raises lift up to the critical angle, beyond which the airflow separates and the wing stalls.

The angle of attack at which the wing produces maximum lift and beyond which it stalls. It is essentially constant regardless of weight, speed or load factor, so a stall can occur at any speed.

A loss of lift caused by airflow separation from the wing when the critical angle of attack is exceeded. Recovery requires reducing the angle of attack, typically by lowering the nose.

The ratio of lift produced to the aircraft's weight, expressed in g. It increases in turns and manoeuvres, raising stall speed and structural stress, and is limited by the aircraft's certification category.

The repetition by a pilot of safety-related elements of an air traffic control clearance or instruction. It allows the controller to verify that the message was received and understood correctly.

A prescribed pattern flown by aircraft around an aerodrome to sequence arrivals and departures safely. It normally includes crosswind, downwind, base and final legs, with turns in a specified direction.

A discontinued approach and landing, initiated when a safe landing cannot be assured. The pilot applies power, climbs and follows the published or instructed procedure to rejoin the circuit or approach.