Drone acronym glossary

Beyond Visual Line-of-Sight

Operation beyond the sight of the pilot and any observer. Safety then relies on other means (detect-and-avoid, procedures, airspace choice). Since 4 Nov. 2025, lower-risk BVLOS (uncontrolled airspace, below 122 m (400 ft), away from populated areas and aerodromes) is allowed with a Level 1 Complex Operations pilot certificate and an RPAS operator certificate (RPOC), without an SFOC. Higher-risk cases still require an SFOC.

Command and Control link

The data link between the control station and the RPA: it carries commands (uplink) and aircraft status (downlink). Its loss triggers 'lost-link' procedures (return-to-home, auto-land, etc.).

Canadian Aviation Regulations

The federal regulations governing all civil aviation in Canada: aircraft registration, licences and certificates, rules of the air, airspace. One of its parts is devoted to remotely piloted aircraft systems and sets the operating categories, the required certificates and the flight limits. It is the reference text behind almost every air-law question on the exam.

Detect and Avoid

The capability (sensors, systems and procedures) to detect other aircraft, obstacles or hazards and act to avoid a collision. Essential for BVLOS, where human see-and-avoid is no longer possible.

Extended Visual Line-of-Sight

The pilot does not personally see the RPA: one or more visual observers keep unaided visual contact with the airspace in which the aircraft is flying, sufficient to detect air-traffic conflicts and other hazards, and tell the pilot what is needed to avoid them. A defined operating category since the 2025 amendments. It keeps human see-and-avoid while extending range.

Maximum Take-Off Weight

The maximum weight at which an aircraft may take off. Note: the regulations actually categorize RPA by operating weight: microdrone < 250 g (exempt from registration and pilot certificate, but no hazardous flying), small 250 g–25 kg (basic or advanced), medium > 25–150 kg, and > 150 kg (SFOC required).

Remotely Piloted Aircraft

The aircraft itself, flown remotely by a pilot who is not on board. It is classified by operating weight: microdrone (< 250 g), small RPA (250 g–25 kg) and medium RPA (> 25–150 kg).

Remotely Piloted Aircraft System

The complete, configurable set of elements made up of the remotely piloted aircraft (RPA), its control station, the command-and-control (C2) links and any other elements required during flight. It is this 'system' (not just the drone) that is regulated.

Remote Pilot-in-Command

The pilot responsible for the safe conduct of the flight and holder of the required certificate: Basic Operations, Advanced Operations (with the advanced exam and a flight review) or, since 2025, Level 1 Complex Operations (lower-risk BVLOS). The Canadian regulations use the terms 'pilot' and 'pilot-in-command' rather than the abbreviation RPIC, which is chiefly U.S. usage.

Special Flight Operations Certificate

Special Flight Operations Certificate – RPAS

An official authorization issued for operations that fall outside the standard framework (basic, advanced, Level 1 complex): e.g. RPA over 150 kg, operations at an advertised event, certain higher-risk BVLOS flights, or any case the Minister deems necessary. The operator applies; the risk is assessed and conditions are imposed.

Standard 922 — RPAS Safety Assurance

Standard 922: RPAS Safety Assurance (and manufacturer's declaration)

Standard 922 sets the technical requirements an RPAS must meet for a given operational category (near or over bystanders, controlled airspace, complex operations). The manufacturer files a declaration with the Minister attesting that its model meets them; without that declaration, the RPAS cannot be used for advanced or complex operations.

Visual Line of Sight

Visual Line-of-Sight

Operating mode in which the pilot keeps unaided, direct visual contact with the RPA, enough to control it, know its position and see-and-avoid other aircraft. Required for basic and advanced operations. When a visual observer takes over that watch of the surrounding airspace, the operation becomes extended VLOS (EVLOS).

Visual Observer

A trained crew member who assists the pilot by keeping the RPA and surrounding airspace in sight and communicating with the pilot for see-and-avoid. The visual observer is what makes extended VLOS (EVLOS) possible.

Controlled and uncontrolled airspace (Classes A to G)

Canada divides airspace into seven classes: A, B, C, D and E are controlled (ATC service provided) and G is uncontrolled; F is special use. Basic RPAS operations take place only in uncontrolled airspace (Class G); controlled airspace requires an advanced operation and NAV CANADA authorization.

Aerodrome

Aerodrome = any place (land, water or surface) used for the arrival, departure and movement of aircraft: the broadest term. Airport = an aerodrome holding a valid airport certificate. Heliport = an aerodrome intended for helicopters. Proximity to any of these imposes additional requirements on RPAS flight, to be assessed during the site survey.

Above Ground Level

Altitude measured relative to the ground directly below the RPA. General RPAS ceiling: 400 ft (122 m) AGL, or up to 100 ft (30 m) above a building or structure when the aircraft is within 200 ft (61 m) laterally of it.

Aerodrome Traffic Frequency

Frequency used at uncontrolled aerodromes that have no mandatory frequency, to broadcast intentions; where no UNICOM or assigned frequency exists, the default is 123.2 MHz. Published in the Canada Flight Supplement.

Canada Flight Supplement

Official directory of Canadian aerodromes, published by NAV CANADA and revised every 56 days, listing runways, frequencies (MF and ATF), services and communications. Reference source for checking an aerodrome's environment before an RPAS flight.

Advisory area (Class F)

Class F airspace flagging a high concentration of an activity, shown by a suffix (e.g., S: soaring, A: aerobatics, P: parachuting, T: training, H: hang gliding). Flight is not prohibited but caution is required: avoid or transit with vigilance.

Danger area

Area established in international airspace (over international waters) to warn of hazardous activities. Because Canada cannot prohibit flight in international airspace, it is called a 'danger' area rather than 'restricted'.

Restricted area (Class F)

Class F airspace where flight is prohibited or restricted per published conditions; entry requires permission from the user agency. Must be identified during the site survey before any RPAS flight.

Mandatory Frequency

Radio frequency in force at certain uncontrolled aerodromes where aircraft must carry a radio, broadcast their intentions and maintain a listening watch. Published in the Canada Flight Supplement; a key awareness factor for RPAS flight near an aerodrome.

Above Sea Level

Above Sea Level or Mean Sea Level

Altitude measured relative to mean sea level. Airspace floors and ceilings on aeronautical charts are often given in ASL, unlike the 400 ft drone limit which is in AGL. Never confuse the two references.

NAV Drone (RPAS planning and authorization app)

NAV CANADA web and mobile application to visualize airspace, assess aerodrome proximity and request authorization to fly in controlled airspace. An essential planning and site-survey tool for advanced operations.

Notice to Airmen

Notice distributed by telecommunication reporting the establishment, condition or change of any aeronautical facility, service, procedure or hazard, including RPAS restrictions. Reviewing them before flight is mandatory (site survey).

Graphic Area Forecast

Set of charts covering a large region: a "clouds and weather" chart and an "icing, turbulence and freezing level" chart. Issued four times a day; each issue covers 12 h (charts valid at 0, +6 and +12 h) and adds a further 12 h outlook. It is the primary source of weather between aerodromes, where no TAF applies.

Global Navigation Satellite System

Global Navigation Satellite System or Global Positioning System

Satellite positioning: GNSS is the general category; GPS (American) is its best-known system. It gives the RPAS its position, altitude and speed (RTH, position hold). Accuracy can degrade (interference, jamming, poor satellite geometry): if the signal is lost, the pilot remains responsible for controlling the RPA.

International Standard Atmosphere

Reference model of the atmosphere: 15 °C and 1013.2 hPa (29.92 in Hg) at sea level, with temperature falling about 2 °C per 1,000 ft (1.98 °C/1000 ft). It underpins altimetry and performance; real deviations (heat, altitude) raise density altitude and cut the RPAS's lift and performance.

Aerodrome routine meteorological report

Aerodrome Routine Meteorological Report

Hourly observation of the actual weather at an aerodrome: wind, visibility, present weather, cloud, temperature and dew point, altimeter setting. It is an observation (past or present), not a forecast; the RPAS pilot reads it to judge whether a visual line-of-sight (VLOS) flight is feasible before launch.

Nautical Mile

Aviation unit of distance: 1 NM = 1.852 km ≈ 1.15 statute miles (SM). Used for navigation distances and regulatory radii (e.g., distance from an aerodrome). The related speed unit is the knot (1 NM/h). Not to be confused with the statute mile.

Statute Mile

Unit used mainly for ground visibility in Canadian METARs and TAFs: 1 SM = 1.609 km. Shorter than the nautical mile (NM). Remember: in Canada visibility is given in statute miles, not nautical miles.

aerodrome special meteorological report

Aerodrome Special Meteorological Report

Non-routine observation issued between the hourly METARs when a significant change occurs (drop in visibility or ceiling, onset or end of a thunderstorm, marked wind shift). Flags a sudden deterioration that can compromise a VLOS flight.

Aerodrome forecast

Terminal Aerodrome Forecast

Forecast of the weather expected within about 5 NM of an aerodrome, for a set period (often 24 to 30 h in Canada). Unlike the METAR, it is a forecast; used to pick a flight window, but it does not cover the area between aerodromes.

Coordinated Universal Time

Coordinated Universal Time (Zulu time, Z)

Worldwide reference time used across aviation (METAR, TAF, GFA, NOTAM) to avoid time-zone confusion; marked "Z". The pilot must convert it to local time (in Quebec: UTC−5 in winter, UTC−4 in summer).

Magnetic variation

Magnetic Variation (Declination)

Angle between true (geographic) north and magnetic north at a given place, expressed East or West. VNC and VTA charts show it with isogonic lines; it must be applied to convert a true heading to a magnetic heading when navigating, because the compass points to magnetic north.

Ceiling and visibility

The ceiling is the height above ground of the lowest broken (BKN) or overcast (OVC) cloud layer, or the vertical visibility when there is no defined layer. Visibility is the greatest horizontal distance at which prominent objects can be seen. Read from the METAR and TAF, both determine whether a visual (VLOS) flight is still possible: the pilot must keep the RPA in direct sight.

VFR Navigation Chart

VFR Navigation Chart and VFR Terminal Area Chart

Aeronautical charts for visual flight. The VNC (1:500,000 scale) shows terrain, obstacles, aerodromes and airspace structure; the VTA (1:250,000), more detailed, covers the areas around major airports. The RPAS pilot uses them to identify controlled airspace and obstacles before a VLOS flight.

C-rating (discharge rate)

Multiplier expressing the maximum current a battery can safely deliver (or accept while charging) relative to its capacity: max current ≈ C-rating × capacity (Ah). E.g. 5 Ah at 20C = 100 A. Too low a rating for the motor's demand causes overheating, voltage sag and power loss.

Crew Resource Management

Effective use of all available resources (people, equipment, information) to conduct the flight safely. For an RPAS the "crew" includes visual observers and payload operators: clear role assignment, communication and read-back, shared situational awareness and coordinated emergency procedures. Its aim is to reduce human error through teamwork.

Electronic Speed Controller

Circuit that converts the battery's DC into three-phase current to drive a brushless electric motor, setting its speed per the flight controller's commands. A failing or overheating ESC (excess current, wrong rating) can cut a motor and cause loss of control on a multi-rotor. It is also called a "speed controller".

Human Factors

The study of human capabilities and limitations that affect flight safety: physiology (vision, hearing, disorientation, fatigue, CO effects), psychology (decision-making, situational awareness, stress, workload, hazardous attitudes), the pilot-equipment relationship (automation complacency, checklists) and interpersonal relations. A standalone exam knowledge area; human error is the leading cause of incidents.

Firmware

Embedded software that runs the RPA, the control station and their components (flight controller, ESC, C2 link). Keep it updated per the manufacturer's instructions: an update can fix defects, change performance or restore compliance; an outdated version or an interrupted update can leave the aircraft unfit to fly. Version control is part of keeping the RPAS in a serviceable condition.

Geofencing (virtual geographic boundary)

Manufacturer software feature that sets virtual 3-D boundaries preventing the RPA from entering certain zones (e.g. near airports) or leaving them. A useful aid, but NOT an authorization or regulatory guarantee: the pilot remains solely responsible for airspace rules. Check airspace with the official tool (NAV Drone) rather than relying on it.

Illness, Medication, Stress, Alcohol, Fatigue, Emotion

Illness, Medication, Stress, Alcohol, Fatigue, Emotion (pilot self-assessment)

Mnemonic self-assessment the pilot runs BEFORE every flight to judge fitness: Illness, Medication, Stress, Alcohol, Fatigue and Emotion (sometimes Eating). Any single adverse factor (fatigue or a medication, for instance) can be reason to postpone. It mirrors the "pilot and operating environment" factors in the Human Factors knowledge area.

Inertial Measurement Unit

Sensor combining accelerometers and gyroscopes (sometimes a magnetometer) that measures the RPA's acceleration, attitude and angular rates; its data feed the flight controller to stabilize the aircraft. It must be calibrated on a stable, level surface; a poorly calibrated or disturbed IMU drifts and causes instability, position drift or tip-over.

Lithium-Polymer

Lithium-polymer battery

High-energy-density rechargeable battery that powers most small RPAs. Never fly a swollen, punctured or damaged pack: overcharge, deep discharge or a short can trigger thermal runaway and fire. Cold reduces capacity and causes voltage sag. Charge and store per the manufacturer (storage voltage) and follow TDG rules when transporting.

Return-To-Home

Return-to-Home

Automatic failsafe that flies the RPA back to a recorded home point on loss of the command-and-control (C2) link or on low battery. It needs a correct home point and a reliable GNSS or GPS fix; depending on settings the aircraft may climb to a preset altitude then return in a straight line, a collision risk with obstacles. It replaces neither the pilot's monitoring nor the emergency procedures.

Aerodrome Advisory Service

An information service provided by a NAV CANADA flight service station (FSS) at an uncontrolled aerodrome: runway in use, wind, altimeter setting, known traffic. It is not control: no clearance is issued and the pilot remains responsible for separation. Remote variant: remote aerodrome advisory service (RAAS).

Aviation weather advisory

A weather advisory flagging a phenomenon that could affect flight safety and is not already shown on the graphic area forecast (GFA): ceiling or visibility dropping below visual-flight thresholds, moderate icing or turbulence, strong surface winds. One step below a SIGMET, but aimed squarely at the conditions that compromise a visual flight.

Air Navigation Service Provider

The organization that provides a country's air navigation services; in Canada, NAV CANADA. It is the body whose authorization is needed to enter controlled airspace with a remotely piloted aircraft, requested through the NAV Drone app. The regulation itself says 'air traffic service provider'.

Air traffic control

Air Traffic Control

The service that separates aircraft and issues clearances and instructions in controlled airspace and around controlled airports. For an RPAS flight in controlled airspace, authorization is obtained before flight from the service provider (NAV CANADA, usually through NAV Drone), not by a radio call. Instructions received from a control unit must then be complied with.

Automatic Terminal Information Service

A continuous recorded broadcast, on a dedicated frequency, of an airport's current information: observed weather, runway in use, altimeter setting and special notices. Each update carries a letter (Alpha, Bravo…) used to confirm you have the current version. Exam trap: as on the radio, its wind is given in degrees magnetic, whereas METAR and TAF give degrees true.

Air traffic services

Air Traffic Services

Umbrella term covering every service provided to aircraft: air traffic control (ATC), advisory services and flight information services. In Canada they are delivered by NAV CANADA. An "ATS unit" may therefore be a control tower, an area control centre or a flight service station (FSS), and not all of them issue clearances.

Automated Weather Observation System

An automated station that measures the full suite of aerodrome observation elements (wind, visibility, ceiling, temperature, dew point, altimeter setting) and produces a METAR with no human involvement. The report then carries "AUTO" in its body.

Broken

Code de nébulosité du METAR et de la prévision d'aérodrome : ciel fragmenté, la somme des couches observées couvrant de 5/8 à moins de 8/8 du ciel (5 à 7 octas). Avec OVC, c'est l'un des deux seuls codes qui constituent un plafond — celui-ci se situe à la hauteur de la première couche BKN ou OVC, ou à la visibilité verticale (VV) lorsque le ciel est obscurci. La hauteur suit le code, en centaines de pieds au-dessus de la station : BKN010 se lit « couche fragmentée à 1 000 pi ». Piège d'examen : SCT ne compte jamais pour le plafond, BKN oui.

Mist

Code du groupe de temps présent d'un METAR, dans la catégorie des phénomènes d'obscurcissement : brume. Au Canada, on code BR lorsque la visibilité est de 5/8 SM ou plus (environ 1 km) ; sous ce seuil, le même phénomène devient du brouillard (FG). Ce seuil est une différence canadienne apportée à la table de code internationale, et c'est précisément ce que l'examen vérifie : brume et brouillard ne se distinguent pas par leur nature, mais par la visibilité. Une brume signalée reste une menace directe pour la visibilité directe (VLOS).

Cumulonimbus

Abbreviation for cumulonimbus, the thunderstorm cloud, used as-is in METARs, TAFs and the graphic area forecast (GFA). It brings microbursts, hail, lightning and shear whose effects are felt kilometres from the cloud: its presence means stopping operations, not merely standing off.

Cannabidiol

A cannabis-derived compound sold as oils, capsules or creams and often presented as non-intoxicating. Products on the market are not THC-free and can cause drowsiness or reduced alertness: cannabidiol therefore belongs in the IM SAFE fitness-to-fly self-check just like any medication, and an impaired pilot does not fly.

Centre of gravity

The point where the aircraft's weight acts, and so the balance point it pivots around. Too far aft and the aircraft is unstable in pitch: the nose tends to rise on its own and recovery may be impossible; too far forward and it stays stable but nose-heavy, with reduced performance. Any added payload moves it, hence the pre-flight weight-and-balance check.

Carbon monoxide

An odourless, colourless, tasteless gas produced by any combustion: the engine of the vehicle used as a ground control station, a space heater, a generator. It binds to haemoglobin in place of oxygen and starves the brain: headache, nausea, blurred vision, degraded judgement, all symptoms easily blamed on fatigue or cold. The classic winter scenario is operating from a vehicle with the engine running.

Control area

Control Area

Controlled airspace designated in the Designated Airspace Handbook (DAH): in Canada, the Southern, Northern and Arctic Control Areas. Their base lies far above the altitudes permitted to drones; what concerns a drone pilot near the ground is rather control zones and terminal control areas.

Canada Water Aerodrome Supplement

The directory of Canadian water aerodromes: the bodies of water used for landing and take-off, with their coordinates, procedures and frequencies. It is the counterpart of the Canada Flight Supplement (CFS) for floatplanes, and worth checking before flying near a lake or river, where you would not expect an aerodrome.

Designated Airspace Handbook

The publication (TP 1820) that officially designates Canadian airspace: classes, control areas and control zones, and every Class F area (CYR, CYA, CYD) with their limits, hours of activity and controlling agency. VNC and VTA charts are the picture; the DAH is the reference text. The abbreviation stays DAH in French.

Detect, Estimate, Choose, Identify, Do, Evaluate

DECIDE decision-making loop (FAA aid)

A six-step aid for deciding under pressure: Detect, Estimate, Choose, Identify, Do, Evaluate. A useful method, but a US (FAA) tool: Transport Canada does not use it and does not require it on the exam; the Canadian model is "pilot decision making".

Differential Global Positioning Service

Differential GPS

A technique that improves GPS accuracy by broadcasting corrections computed by a ground station whose exact position is known: the receiver applies them and error drops from metres to centimetres. That is what makes precision automatic landings and survey work possible.

Department of National Defence

The federal department responsible for the Canadian Armed Forces. In aviation it operates its own aerodromes and much of the Class F airspace: restricted areas (CYR) and advisory areas (CYA). Access to a restricted area goes through the user agency listed in the Designated Airspace Handbook (DAH).

Dilution of Precision

A figure expressing how satellite geometry affects positioning quality: many satellites well spread across the sky give a low DOP and good accuracy; satellites bunched together or masked by buildings or terrain raise the DOP and degrade the fix. Hence the pre-flight check of satellite count and the value shown by the RPAS.

Environment and Climate Change Canada

The federal department responsible for the country's weather observations and forecasts. In aviation, its meteorologists write, under an agreement with NAV CANADA, the forecasts the pilot reads: TAF, graphic area forecast (GFA), AIRMET, SIGMET. The METAR is an observation: it comes from an automated station or an observer, and NAV CANADA distributes all of these products.

Emergency Medical Services

Ambulance and emergency first-response services. Flight preparation includes finding their contact details and the access route to the site, and recording them in the emergency plan along with those of local authorities.

Emergency Security Control of Air Traffic

Emergency Security Control of Air Traffic Plan

An air-defence plan set up with NORAD: in an air-defence emergency it allows air traffic over Canada to be restricted or halted. It is the mechanism capable of grounding Canadian civil aviation nationwide. The word 'security' here means national security and defence, not flight safety.

Federal Aviation Administration

The civil aviation authority of the United States. Its rules do not apply in Canada, and this is a common trap: much of the study material found online ('Part 107' rules, the DECIDE and PAVE mnemonics, the abbreviation 'RPIC') is FAA material and does not match the Canadian exam, which follows the CARs and TP 15263.

Few

Code de nébulosité du METAR et de la prévision d'aérodrome : quelques nuages, la somme des couches couvrant de moins de 1/8 à 2/8 du ciel (1 à 2 octas). C'est la plus faible nébulosité signalée au-dessus de SKC (ciel clair) et de CLR (clair au-dessous de 25 000 pi, réservé aux stations d'observation automatisées). Comme SCT, une couche FEW ne constitue jamais un plafond.

Fog

Code du groupe de temps présent d'un METAR, dans la catégorie des phénomènes d'obscurcissement : brouillard, c'est-à-dire un nuage posé au sol. Au Canada, FG est codé lorsque la visibilité tombe sous 5/8 SM (environ 1 km) ; à 5/8 SM ou plus, on code de la brume (BR). Les descripteurs MI (mince), BC (bancs) et PR (partiel) ne se combinent qu'avec FG — par exemple MIFG — et FZFG désigne le brouillard givrant. Du brouillard sur le site interdit simplement le décollage : sans visibilité directe, le vol perd son fondement légal.

Flight Information Centre

A NAV CANADA unit reached by telephone for an interpretive weather briefing, NOTAM information and flight plan filing. Toll-free: 1-866-WXBRIEF (1-866-992-7433). Not to be confused with a flight service station (FSS), which serves one aerodrome.

Flight Level

An altitude expressed in hundreds of feet on an altimeter set to standard pressure (29.92 in. Hg or 1013.2 mb): FL 180 is 18,000 ft in the standard atmosphere. Flight levels are used to separate aircraft at high altitude; a drone never flies there, but you meet them when reading airspace ceilings and forecasts.

First-Person View

Flying from the aircraft's live video feed (goggles or a screen) instead of watching the aircraft itself. This mode does not by itself provide the unaided, direct visual line-of-sight (VLOS) required of the pilot: direct visual contact with the aircraft must be maintained by other means.

Flight Service Station

A NAV CANADA unit that provides information, not control: runway in use, wind, altimeter setting and known traffic, delivered as the aerodrome advisory service (AAS) at an uncontrolled aerodrome. Remember the exam distinction: a flight service station informs, it never authorizes.

Flight Termination System

A device that ends the flight in a controlled way when the situation becomes unmanageable (cutting the motors, deploying a parachute, forcing a landing) in order to protect property and avoid serious injury to people on the ground. The abbreviation comes from manufacturer documentation, not from Transport Canada, which writes the term out in full.

Eastern Standard Time and Eastern Daylight Time

Eastern Canada's time zones: EST = UTC−5 in winter, EDT = UTC−4 in summer (HNE and HAE in French). Aeronautical products (METAR, TAF, graphic area forecast, NOTAM) are all issued in Coordinated Universal Time (UTC), so convert before planning a flight window. Trap: in a NOTAM, 'EST' means estimated time, not the time zone.

Horizontal Dilution of Precision

The horizontal component of dilution of precision (DOP): how much confidence to place in the lateral position computed by the GNSS. It is the value many flight apps display before take-off, next to the satellite count.

International Civil Aviation Organization

The specialized United Nations agency, headquartered in Montréal, that sets international civil aviation standards: four-letter location indicators, radio phraseology, the International Standard Atmosphere (ISA), weather message formats. Those standards are carried into the CARs and Canadian publications.

Instrument Flight Rules

The rules followed by an aircraft navigating on instruments, most often under air traffic control, including in cloud. An IFR flight can therefore descend toward a runway in poor visibility along a published approach path: that is one reason control zones and the distances to keep around airports exist.

Innovation, Science and Economic Development Canada

The federal department that manages the radio spectrum: its rules govern command-and-control link frequencies (2.4 GHz, 5.8 GHz) and the use of aeronautical radio. It is this department, not Transport Canada, that issues the Restricted Operator Certificate (ROC-A) required to transmit on aeronautical frequencies.

International Telecommunication Union

The United Nations agency that allocates radio spectrum among countries and services: this is the level at which the bands used by aviation, GNSS and drone links are assigned. Pilots never deal with the ITU directly; in Canada, ISED applies those allocations.

Limited Weather Information System

A reduced automated station: it measures only wind, temperature, dew point and altimeter setting, with no visibility and no ceiling. The direct consequence for a visual flight: a site served by an LWIS tells you nothing about the two parameters that most often decide whether the flight is feasible.

Distress signal

Signal international de détresse en radiotéléphonie, prononcé de préférence trois fois au début de la première communication. Il annonce un danger grave et imminent et demande un secours immédiat. Priorité absolue : toute station qui l'entend cesse d'émettre et reste à l'écoute, et la direction du trafic revient à la station en détresse ou à celle qui la relaie ; faute de contact sur la fréquence en usage, on répète l'appel sur 121,5 MHz. Ce n'est pas un acronyme et il n'a pas d'expansion : le guide d'étude du certificat restreint d'opérateur radio précise seulement que le mot se prononce comme l'expression française « m'aider ». MAYDAY appartient à la bande aviation, jamais au canal interne d'équipage.

Maximum Elevation Figure

The large figure printed in the centre of each quadrangle on a VNC chart: it gives, in thousands and hundreds of feet ASL, either the elevation of the highest terrain in the quadrangle plus 328 ft (100 m), or that of the highest known obstruction, whichever is higher. It is not a minimum flight altitude, but a quick gauge of how high the terrain and obstacles reach.

Nominal Ocular Hazard Distance

The distance beyond which a laser beam no longer poses a hazard to the eye. Anyone planning to operate a laser outdoors in airspace shared with aircraft (a laser show or a drone-mounted laser) calculates it and files a notice with Transport Canada, which validates it through an aeronautical assessment before authorizing the operation. Note that the abbreviations do not match letter for letter: DOCN comes from the French term, NOHD from the English.

No Radio

Aircraft Without Radio (No Radio)

Said of an aircraft with no radio, or whose radio has failed: it makes no calls and hears none. Specific arrival and departure procedures exist for it at uncontrolled aerodromes and controlled airports alike (prior arrangement with the tower, light signals); hence the rule never to assume, near an aerodrome, that the traffic heard on the radio is the only traffic there. Related abbreviation: RONLY, receiver-only aircraft.

National Research Council Canada

The federal research agency, which also keeps Canada's official time. Two of its products serve the drone pilot directly: the official sunrise and sunset tables, which determine day, night and twilight, and the drone flight site selection tool referenced by the AIM.

Operator

Aerodrome operator (Canada Flight Supplement entry)

An entry code in the Aerodrome/Facility Directory of the Canada Flight Supplement (CFS): it gives the name and telephone number of the aerodrome operator. It is the line to look for when you need to reach the operator, for example before an operation near the aerodrome. The code is not translated.

Overcast

Code de nébulosité du METAR et de la prévision d'aérodrome : ciel couvert, la somme des couches atteignant 8/8 du ciel (8 octas). Comme BKN, OVC constitue un plafond : OVC007 se lit « ciel couvert à 700 pi » et fixe le plafond à 700 pi au-dessus de la station. C'est la nébulosité maximale signalée ; seule la visibilité verticale (VV) s'y substitue lorsque la couche part de la surface et obscurcit totalement le ciel, ce qui donne un plafond dit obscurci.

Urgency signal

Signal international d'urgence en radiotéléphonie, répété de préférence trois fois au début de la première communication d'urgence. Il annonce une situation qui met en cause la sécurité d'un aéronef, d'un autre véhicule ou d'une personne se trouvant à bord ou en vue, mais qui n'exige PAS de secours immédiat : c'est exactement ce qui le sépare de MAYDAY. Il prime sur toutes les communications sauf celles de détresse, et les stations qui l'entendent restent à l'écoute au moins trois minutes. Ce n'est pas un acronyme et il n'a pas d'expansion : le guide d'étude du certificat restreint d'opérateur radio note seulement que « PAN » se prononce comme le mot français « panne ».

Pilot-in-command, Aircraft, enVironment, External pressures

PAVE risk-assessment checklist (FAA aid)

A memory aid that sorts flight risk into four families: Pilot, Aircraft, enVironment and External pressures. Like DECIDE, it is a US (FAA) tool, not adopted by Transport Canada and outside the Canadian exam syllabus.

Pilot-in-Command

The pilot responsible for the conduct of the flight, from preparation through landing: the one who decides whether to fly and who answers for any breach. The abbreviation 'RPIC', common in US material, appears in no official Canadian source.

Procedures

Local procedures (Canada Flight Supplement entry)

An entry code in the Aerodrome/Facility Directory of the Canada Flight Supplement (CFS): it gathers the aerodrome's own procedures and restrictions (circuits, use restrictions, noise abatement). It is where you learn, for example, that an aerodrome may be used in daylight only. Like OPR, the code is the same in both languages.

Probability 30%

Probability group (TAF)

Groupe d'une prévision d'aérodrome indiquant une probabilité de 30 % que les valeurs prévues diffèrent de celles annoncées pendant la période visée (PROB40 pour 40 %). Il s'insère juste avant la période de validité, donnée en heures UTC entières : PROB30 2817/2821 signifie qu'entre 1700Z et 2100Z le 28e jour du mois, le phénomène a 30 % de chances de se produire. Il est réservé aux dangers pour l'aviation — orages, précipitations verglaçantes, cisaillement du vent à 1 500 pi AGL ou au-dessous, plafonds et visibilités opérationnellement significatifs. Piège d'examen : c'est la probabilité de l'événement, jamais « 30 % du temps ». Sous 30 %, on n'emploie pas PROB ; à 50 % ou plus, on utilise BECMG, TEMPO ou FM.

Pre-Validated Declaration

A safety assurance declaration with an added first step: the declarant first submits to Transport Canada a file showing how the product will be used and how it meets the applicable Standard 922 requirements; once the application is accepted, a letter of acceptance allows the declaration to be made, within two years. It applies to medium remotely piloted aircraft flown VLOS near or over people, and to the most demanding Level 1 complex operations.

Radio Frequency

Radio frequency

Ondes radioélectriques employées par la liaison de commande et de contrôle, le retour vidéo et certaines charges utiles : bandes avec ou sans licence, portée en visibilité optique, gain d'antenne, rapport signal sur bruit. Évaluer l'environnement RF fait partie de l'examen des lieux — repérer les sources de brouillage (Wi-Fi, tours, lignes à haute tension, milieu urbain), au besoin par un balayage RF ou un analyseur spectral, puis placer les antennes selon les indications du fabricant. À ne pas confondre avec l'autre « RF » de la liste officielle des abréviations aéronautiques, qui désigne l'arc jusqu'au repère (radius to fix), une jambe d'approche aux instruments sans aucun rapport avec la radiofréquence.

Restricted Operator Certificate with Aeronautical Qualification

A certificate issued by Innovation, Science and Economic Development Canada authorizing the use of an aeronautical radio. It becomes necessary as soon as an RPAS pilot transmits on an aeronautical frequency: mandatory frequency (MF), aerodrome traffic frequency (ATF), or contact with an air traffic services unit. It is earned by passing an exam with an accredited examiner, based on study guide RIC-21.

Acknowledgement of receipt

Mot conventionnel signifiant « j'ai reçu en entier votre dernière transmission ». Il accuse réception, rien de plus : ce n'est ni un accord (AFFIRMATIF), ni un engagement à exécuter (WILCO), ni un collationnement (RELISEZ). La phraséologie française canadienne le conserve tel quel, alors qu'elle traduit NÉGATIF, TERMINÉ, RELISEZ ou RESTEZ À L'ÉCOUTE : ROGER n'est donc pas un anglicisme toléré, c'est la forme officielle. Ce n'est pas un acronyme et aucune expansion ne lui est associée dans les sources consultées. Distinguer ROGER, WILCO et AFFIRMATIF est un piège d'examen classique.

Revolutions per minute

Vitesse de rotation d'un moteur, exprimée en tours par minute (tr/min). Sur un multirotor, tout le pilotage passe par les écarts de régime entre moteurs : il n'y a aucune gouverne mobile, et c'est le régulateur de vitesse (ESC) qui traduit les ordres du contrôleur de vol en variations de régime. Le régime maximal d'un moteur sans balais vaut approximativement Kv × tension de la batterie : il dépend donc du moteur et de la batterie, pas de l'hélice. Abréviation d'usage industriel : elle ne figure ni dans la liste officielle des abréviations aéronautiques ni dans le guide d'étude de l'examen, qui écrivent « tours par minute » ou « tr/min ».

RPAS Safety Assurance Declaration

A declaration filed with the Minister by the declarant (usually the manufacturer) attesting that an RPAS model meets the Standard 922 technical requirements for a given type of operation. Without it, the aircraft cannot be used for advanced or complex operations: before buying or flying, the pilot checks that the model is declared for the intended operation.

Search and Rescue

The federal system responsible for locating and rescuing aircraft and people in distress. For a drone pilot the rule is simple: never interfere with an operation in progress (SAR operations are often the subject of a NOTAM) and stay well clear of the participating aircraft, which often manoeuvre very low.

Satellite-Based Augmentation System

A system that broadcasts corrections by satellite to improve GNSS accuracy and integrity over a wide area; in North America that system is WAAS.

Scattered

Code de nébulosité du METAR et de la prévision d'aérodrome : ciel épars, la somme des couches couvrant de 3/8 à 4/8 du ciel (3 à 4 octas). Une couche SCT ne constitue jamais un plafond, si basse soit-elle : SCT002 n'en est pas un, alors que BKN020 en est un. C'est l'une des confusions les plus fréquentes à la lecture d'un METAR. Le type de nuage convectif s'ajoute sans espace lorsqu'il est observé, par exemple SCT025TCU pour des cumulus bourgeonnants épars à 2 500 pi.

Significant Meteorological Information

A warning issued for a hazardous phenomenon occurring or expected: thunderstorms, severe icing, severe turbulence, volcanic ash. It is the most urgent product in the weather chain: a SIGMET in force over the flight site is by itself reason to cancel or postpone.

Transport Canada Aeronautical Information Manual

Publication d'information aéronautique qui réunit en un seul document les règles de l'air et les procédures applicables au Canada, organisée en chapitres (GEN, AIR, COM, MET, RAC, MAP, SAR, ATP…) et rééditée deux fois l'an. Ce n'est pas un texte réglementaire : le RAC fait foi, l'AIM de TC explique et complète. C'est néanmoins l'une des sources officielles admises pour préparer l'examen, avec le RAC et le guide d'étude. Attention à la forme du sigle : la publication s'abrège « AIM de TC » en français et « TC AIM » en anglais, car « AIM » seul désigne, dans la liste officielle des abréviations, la gestion de l'information aéronautique de NAV CANADA — un tout autre sens.

Towering Cumulus

Towering cumulus

A cumulus growing strongly upward: the middle stage of the cumulus → TCU → cumulonimbus (CB) sequence. Watching one build is watching a thunderstorm form; pack up before the CB stage, not after. Note: in aviation publications, 'TCU' can also stand for terminal control unit.

Transportation of Dangerous Goods

The federal Act and Regulations governing the carriage of dangerous goods: explosives, compressed gases, flammable liquids, lithium batteries and the like. An RPA carrying them falls under that regime in addition to the CARs. The English documents write 'TDG Act' and 'TDG Regulations'.

Transportation Safety Board of Canada

The independent federal body that investigates transportation accidents and incidents, including those involving a remotely piloted aircraft. It neither regulates nor assigns blame: it determines causes and issues safety recommendations. Certain occurrences must be reported to it directly: an accident involving an aircraft over 25 kg, a serious injury or death caused by contact with a small remotely piloted aircraft, or a collision between a remotely piloted aircraft and a manned aircraft.

Control tower

The unit that controls traffic on the manoeuvring area and in the circuit at a controlled airport. "TWR" is the data code used in the Canada Flight Supplement and in NOTAMs for the tower frequency.

Visual Flight Rules

The rules followed by an aircraft navigating visually, keeping minimum visibility and distance from cloud. This is how most of the small aeroplanes and helicopters a drone may meet are flown, often low and near aerodromes; VNC and VTA charts are made for them.

Vortex Ring State

Vortex ring state

Loss of lift that occurs when a multirotor descends vertically, with no forward speed, into its own downwash: the propellers churn already-disturbed air instead of clean air. Adding power only deepens the descent; the recovery is lateral speed to reach clean air.

Vertical takeoff and landing aircraft

Vertical take-off and landing aircraft

An aircraft able to take off and land vertically, with no runway: every multirotor qualifies, as do fixed-wing hybrids that climb vertically then transition to forward flight for endurance. The French abbreviation in the official list is ADAV; manufacturers and the English exam use VTOL.

Wide Area Augmentation System

North America's satellite-based augmentation system (SBAS): a network of ground stations measures GPS errors and has corrections broadcast by satellite. Most RPAS receivers use it without any action from the pilot; it mainly improves vertical accuracy and positioning integrity.

Undertaking to comply with the instructions received

Mot conventionnel signifiant « vos instructions ont été reçues, comprises et seront exécutées ». Il va donc plus loin que ROGER, qui n'accuse que réception : WILCO engage à exécuter. Comme ROGER, la phraséologie française canadienne le conserve en anglais. L'expansion des lettres n'étant donnée par aucune des sources canadiennes consultées, le champ reste vide plutôt que d'être deviné.

Toll-free flight information centre number (1-866-WXBRIEF)

Not the name of a service but the mnemonic for the toll-free number 1-866-992-7433: the call is routed to the flight information centre (FIC) serving the region it comes from. What you get there is an interpretive weather briefing: a specialist reads the conditions with you instead of leaving you to decode them alone.