KCAA Flight Radio Telephony Operator Licence (FRTOL) key terms

A mandatory repetition back to the issuing controller of safety-critical instructions such as clearances, runway assignments, altitudes, headings and frequencies, confirming the message was received and understood correctly.

The prescribed set of internationally agreed words and sentence patterns used on aeronautical radio so that messages stay short, unambiguous and understood by all stations regardless of native language.

A radiotelephony word meaning the transmission was received in full and understood. It does not mean agreement, approval, or that any requested action will be carried out.

A radiotelephony word meaning the message was understood and the instruction in it will be complied with. It is used only where the pilot or station intends to act on the instruction.

The standard word for answering a question in the positive, used instead of informal words such as yes or yeah to keep radio exchanges unambiguous and internationally consistent.

The standard word for answering a question in the negative or for stating that something is not the case, used instead of no to avoid confusion on a noisy radio channel.

A request for the previous transmission to be repeated in full. It is used when reception was poor or content was missed, and is preferred over informal requests such as repeat please.

A word spoken before restating a message that contained an error, cancelling the earlier version. The receiving station must discard the previous figures or instruction and use only the corrected version.

A phrase telling the other station to wait and that you will call back. It implies no approval or clearance and the waiting station must not act as if permission had been given.

An authorisation from air traffic control for an aircraft to proceed under specified conditions, normally including route, level, and any restrictions, which the pilot must read back before acting.

An instruction to set a specified four-digit code into the aircraft transponder, allowing air traffic control radar systems to identify the aircraft and display its altitude and position.

Airborne radio equipment that replies to ground radar interrogations by transmitting an identity code and, in Mode C or S, pressure altitude, enabling surveillance of the aircraft by air traffic services.

An instruction to press the identification button on the transponder, which causes a distinctive highlight on the controller's radar display so the aircraft can be positively identified.

A ground radar system that transmits interrogations and receives coded replies from aircraft transponders, providing identity, range and altitude information to controllers for separation and identification.

The very high frequency radio band, from 118.000 to 136.975 MHz in civil aviation, used for line-of-sight air-ground voice communication because it gives clear reception and is relatively free of static.

The high frequency band used for long-range aeronautical voice communication over oceans and remote areas, relying on ionospheric skywave propagation that varies with time of day and season.

The allocation of a specific radio channel to a station or service by the competent authority, ensuring that transmissions on that frequency do not cause harmful interference to other users.

The emergency channel 121.5 MHz, monitored continuously by air traffic units and many aircraft so that distress calls, urgency messages and emergency locator transmissions are heard without delay.

The propagation condition in which VHF radio signals travel in nearly straight lines and are blocked by terrain and the earth's curvature, limiting usable range to roughly the visible horizon.

A selective calling system that alerts a specific aircraft by transmitting a coded tone sequence, so crews on long-range flights need not monitor the channel continuously for routine calls.

The spoken distress signal, transmitted three times, indicating that a station is in grave and imminent danger and requires immediate assistance from air traffic services or rescue coordination.

The spoken urgency signal, transmitted three times, used when a station has a serious problem affecting safety but is not in immediate danger and does not yet require immediate assistance.

A transmission beginning with MAYDAY that identifies the station, its position, nature of the emergency, intentions and assistance required, sent on the frequency in use or on the emergency channel.

A transmission beginning with PAN PAN that reports a serious condition affecting safety, such as an engine problem or medical emergency, without immediate danger to the aircraft or persons on board.

The loss of the ability to transmit or receive on the assigned frequency, handled by following published procedures such as squawking 7600, continuing per the last clearance and watching for light signals.

The published set of actions a pilot follows when radio contact is lost, covering transponder code, route continuation, altitude selection and approach timing so controllers can predict the aircraft's behaviour.

A ground instruction given by coloured lamp or signal projector to an aircraft that cannot communicate by radio, with meanings such as steady green for cleared to land and flashing red for stop.

An emergency locator transmitter carried on board that automatically or manually broadcasts a distress signal on 406 MHz and 121.5 MHz to help search and rescue locate a crashed aircraft.

An air traffic services unit such as a tower, approach control or area control centre that provides flight information, alerting and, where applicable, air traffic control to aircraft within its area.

The automatic terminal information service, a continuous recorded broadcast of current weather, runway in use and other essential aerodrome information that pilots acknowledge by quoting an identifying letter.

A coded routine aerodrome weather report issued at fixed intervals, giving wind, visibility, weather phenomena, cloud, temperature, dew point and pressure, which pilots interpret before departure or approach.

The altimeter setting that, when set on the sub-scale, makes the altimeter indicate elevation above mean sea level at the aerodrome, used for terrain clearance and approach procedures.

The altimeter setting that makes the altimeter read height above a specified reference datum, usually the aerodrome, and is used in some countries during approach and landing.

A surface of constant atmospheric pressure shown on the altimeter when set to standard pressure 1013.25 hPa, used above the transition altitude to give a common reference for all aircraft.

A sudden change in wind speed or direction over a short distance, hazardous on approach and departure, often reported by pilots and passed to other aircraft by air traffic control.

A notice distributed to flight crews describing temporary changes or hazards in the aeronautical environment, such as closed runways, unserviceable navigation aids or restricted airspace, that affect flight safety.

The practice of starting and ending a transmission with the calling station's full call sign, and using the abbreviated form only after satisfactory contact has been established between the two stations.

The unique identifier of an aircraft or ground station used on the radio, normally the aircraft registration or the operator's designator plus flight number, spoken clearly to avoid confusion.

The authorisation issued by the national telecommunications or aviation authority permitting an aircraft or ground station to transmit on specified aeronautical frequencies, subject to compliance with conditions.

The Flight Radio Telephony Operator Licence, a personnel certificate confirming the holder has passed examinations in radiotelephony procedures, communications equipment and related regulations and may operate aircraft radio equipment.