Iran CAO CPL Theory key terms

A document issued by the civil aviation authority confirming that an individual aircraft meets the design, construction and maintenance standards required for safe flight, and that it remains legally permitted to operate.

The official document that records the aircraft's nationality and registration marks and identifies the legal owner or operator; it must be carried on board and kept current.

One of the international standards and recommended practices adopted under the Chicago Convention; each Annex covers a technical subject such as rules of the air, licensing or meteorology, and states incorporate them into national law.

A notice distributed to flight crews containing time-critical information about changes or hazards at an aerodrome or in the airspace, such as closed runways, unserviceable navaids or temporary restrictions.

A propeller whose blade angle is adjusted automatically by a governor so that the engine keeps a selected rotational speed as power, airspeed and altitude change.

A self-contained engine-driven ignition unit that generates its own high-tension current, so the spark plugs keep firing even if the aircraft's electrical supply fails.

A pressure vessel, usually containing nitrogen and hydraulic fluid, that stores energy to smooth pressure fluctuations and to allow limited operation of systems such as brakes or landing gear in an emergency.

The combined pressure sources that feed the airspeed indicator, altimeter and vertical speed indicator: pitot pressure from the forward-facing tube and static pressure from the undisturbed air outside the aircraft.

The altimeter sub-scale setting that, when entered, makes the altimeter read aerodrome elevation on the ground; it is derived from the local pressure reduced to mean sea level.

A gyroscopic instrument showing rate of turn and, through a canted gyro, rate of roll; it helps the pilot keep a coordinated turn and serves as a partial-panel reference.

The mass of the aircraft as delivered plus optional equipment, unusable fuel and full engine oil, but without crew, passengers, baggage or usable fuel.

The highest mass the aircraft may have with usable fuel excluded; it limits the payload that can be carried so that structural limits are respected before fuel is added.

The range of centre-of-gravity positions, expressed as fore and aft limits along the fuselage, within which the aircraft can be safely operated at a given mass.

The pressure altitude corrected for the difference between actual temperature and ISA temperature; it represents the altitude the aircraft effectively feels for engine power, lift and take-off distance.

The take-off decision speed: the speed by which a failure is recognised and the aircraft can still stop within the runway, or above which it should continue the take-off.

The shortest runway length for which the distance to stop after an engine failure at V1 equals the distance to continue and reach 35 ft; it defines the required take-off field length.

An aerodrome specified in the flight plan to which an aircraft may divert if landing at the intended destination becomes impossible or inadvisable.

The quantity of fuel that must remain at landing, covering contingency, final approach and missed approach; it is planned in addition to trip fuel and must not be used for normal flight.

The point along the route beyond which the aircraft no longer has enough fuel to return to the departure aerodrome and must continue to a destination or alternate.

A shortage of oxygen reaching body tissues, causing impaired judgement, euphoria and loss of consciousness; at altitude it can develop without warning and is a major risk for pilots.

A false perception of the aircraft's position or motion, usually caused by conflicting sensory inputs in poor visual conditions; the pilot must trust the instruments rather than bodily sensations.

Training and procedures that help flight crew use all available resources, including instruments, checklists and each other, through communication, leadership, workload management and assertiveness.

The International Standard Atmosphere: a defined model of pressure, temperature and density from sea level upward, used as a common reference for altimetry and aircraft performance calculations.

The boundary layer between the troposphere and stratosphere where temperature stops falling with height; its height varies with latitude and season and affects weather and aircraft performance.

A layer in which temperature increases with height instead of decreasing; it stabilises the air, traps haze and smoke below, and can produce wind shear at its top.

A deep convective cloud reaching the tropopause that produces thunderstorms, severe turbulence, icing, hail and heavy rain; it must be avoided by a wide margin.

The angle between true north and magnetic north at a given place, east or west of true north; it is applied when converting between true and magnetic headings.

A ground-based radio navigation aid that transmits signals allowing an aircraft to determine the bearing from the station; it provides course guidance along airways.

The vector relationship between true airspeed and heading, wind velocity, and the resulting ground speed and track, used to calculate headings and drift.

The prescribed pattern of flight around an aerodrome, comprising upwind, crosswind, downwind, base and final legs, used for orderly arrival, departure and landing sequencing.

Any unauthorised presence of an aircraft, vehicle or person on a protected runway area, a major cause of collisions; it demands clear radio calls and strict adherence to clearances.

The lowest altitude that provides a defined clearance above obstacles and terrain along a route or in an area, calculated from charts and used in emergency or off-route situations.

The angle between the wing's chord line and the relative airflow; increasing it raises lift until the critical angle, after which the wing stalls.

The drag created as a by-product of lift, caused by the pressure difference between the wing's upper and lower surfaces; it increases with higher angle of attack and decreases with speed.

The ratio of lift to weight; in a level turn it increases with bank angle, raising the structural stress on the airframe and the speed at which the wing stalls.

The angle of attack at which the airflow separates from the wing and lift reaches its maximum; exceeding it causes a stall at any speed, mass or attitude.

The international radiotelephony distress signal, spoken three times, used when an aircraft is threatened by serious or imminent danger and requires immediate assistance.

The procedure in which a pilot repeats back the essential items of an ATC clearance or instruction so that the controller can confirm it was received correctly.

The four-digit code entered in the transponder, assigned by ATC or selected according to the rules, which identifies the aircraft on radar and can signal emergencies such as 7700.