Iran CAO ATCO Theory key terms

A notice distributed by an aviation authority that informs pilots and controllers about temporary or permanent changes to facilities, services, procedures, or hazards that affect flight safety and are not published in time in other documents.

A fixed 28-day schedule on which significant aeronautical information changes, such as charts and procedures, take effect so that all operators and service providers worldwide can update their data simultaneously and consistently.

The Aeronautical Information Publication: a state-issued document containing the permanent, essential aeronautical information needed for operations in that state's airspace, including regulations, services, and aerodrome data.

Airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification, requiring clearances for operations within it.

A Flight Information Region: airspace of defined dimensions within which flight information service and alerting service are provided, often covering large areas that may contain several smaller control areas and aerodromes.

A control zone: controlled airspace extending upwards from the surface around one or more aerodromes, established to protect aerodrome traffic such as departures, arrivals, and circuit movements.

A terminal control area: controlled airspace normally established at the junction of one or more major air traffic routes near large aerodromes, where arriving and departing traffic is sequenced and separated.

A specified route established for channeling the flow of air traffic as necessary for the provision of air traffic services, published with designators, track directions, and applicable levels.

A published ATS route or portion of one in the form of a corridor with defined width, along which air traffic control service is provided and separated levels and tracks are prescribed.

An authorization for an aircraft to proceed under conditions specified by an air traffic control unit, which is not an instruction to act and does not relieve the pilot of responsibility for safety.

The procedure by which a pilot repeats back safety-related parts of an ATC clearance or instruction, allowing the controller to verify that the message was received and understood correctly.

The spacing maintained between aircraft in flight or on the ground to reduce the risk of collision, achieved through vertical, lateral, or longitudinal distance, or by radar surveillance minima.

The separation of aircraft provided by a controller using radar-derived position information, applying defined horizontal and vertical minima instead of procedural position reporting.

An airborne radio device that replies to secondary radar interrogations, transmitting identification and pressure-altitude information that enables controllers to identify aircraft and monitor their level.

A four-digit octal code assigned to an aircraft that is transmitted by its secondary surveillance radar transponder, allowing the controller to identify that specific flight on the situation display.

The pressure-altitude reporting function of a secondary surveillance radar transponder, which transmits the aircraft's altitude referenced to standard pressure so controllers can verify assigned levels.

The altitude above which pilots set their altimeters to standard pressure and refer to flight levels, and below which they use local altimeter settings and refer to altitudes.

A surface of constant atmospheric pressure related to a datum of 1013.2 hectopascals, expressed in hundreds of feet, used for vertical separation above the transition altitude.

The altimeter setting that, when set on the subscale, causes the altimeter to indicate the aerodrome elevation when the aircraft is on the ground, giving height above mean sea level.

The altimeter setting that makes the altimeter read zero when the aircraft is at the aerodrome reference point, so the instrument indicates height above that aerodrome.

A pressure instrument that converts static pressure into an altitude indication, requiring a correct subscale setting to relate the displayed value to a chosen pressure datum.

A change in wind speed or direction over a short distance, including vertical shear near the surface, which can cause sudden airspeed changes and is hazardous during approach and departure.

A localized downdraft of air that spreads out on hitting the ground, producing a strong and sudden headwind-to-tailwind shift that can cause severe loss of performance close to the ground.

A convective cloud system producing lightning, heavy precipitation, turbulence, and often hail, with strong up- and downdrafts that make penetration hazardous and create wind shear near the surface.

A coded weather term meaning visibility of 10 kilometres or more, no cloud below 5,000 feet or the highest minimum sector altitude, no cumulonimbus, and no significant weather.

A routine aerodrome weather report issued at scheduled times, giving surface wind, visibility, weather, cloud, temperature, dew point, and pressure in a standardized coded format.

A terminal aerodrome forecast that predicts weather conditions at an aerodrome over a stated validity period, used by pilots and controllers to anticipate changes affecting operations.

A manoeuvre in which an aircraft on approach abandons the landing and climbs away, often initiated by the pilot or instructed by the controller when the approach cannot be safely completed.

A published procedure followed when an instrument approach cannot be completed to landing, specifying the climb, turn, and holding or diversion path to be flown while remaining clear of obstacles.

A predetermined manoeuvre keeping an aircraft within a specified airspace while awaiting further clearance, consisting of inbound and outbound legs with defined turns and timing.

The instruction or action of setting a specified four-digit code on the aircraft's transponder, as in squawking an assigned code or the emergency codes 7500, 7600, and 7700.

A radiotelephony urgency signal spoken three times at the start of a call to indicate a condition concerning the safety of an aircraft or person but not requiring immediate assistance.

A radiotelephony distress signal spoken three times at the start of a call to indicate that an aircraft is threatened by serious or imminent danger and requires immediate assistance.

The standardized set of words and sentence patterns prescribed for radiotelephony communication, designed to make transmissions brief, unambiguous, and understood across language boundaries.

A person's continuous perception and understanding of what is happening in the operational environment, including traffic, weather, and own aircraft state, and what it implies for near-term actions.

The amount of mental and physical effort required to perform tasks within a given time, which if excessive or too low can degrade performance, decision quality, and error detection.

A state of reduced vigilance and self-satisfaction arising when conditions seem routine or safe, leading a controller or pilot to miss subtle cues and accept degraded performance.

In radiotelephony, the tendency for listeners to hear what they expect rather than what was said, which can cause misheard callsigns, levels, or instructions during routine exchanges.

A safety-net function of an automated air traffic system that warns the controller when two tracked aircraft are predicted to violate separation minima within a set time.

The Automatic Terminal Information Service: a continuous recorded broadcast of current aerodrome information such as weather, runway in use, and pressure, identified by a code letter.