A B C D E F G H I J K L M N 
safe altitude 100 NM

The lowest altitude that may be used under instrument meteorological conditions (IMC) that will provide a minimum clearance of 1000 ft or, in a designated mountainous region, 1500 or 2000 ft, as appropriate, rounded up to the next 100-ft increment, under conditions of standard temperature and pressure, above all obstacles located in an area contained within a radius of 100 NM of the aerodrome geometric centre.

Fr: altitude de sécurité 100 NM


A manoeuvre during high wind conditions (usually with power off) where floatplane movement is controlled by water rudders and by the opening and closing of cabin doors.

Fr: dérive dirigée

same track

In the application of separation, expression used by ATC to indicate identical tracks or tracks that converge or diverge at an angle of 1° to 44° inclusive.

Fr: même route


Abbreviation for: search and rescue


satellite-based augmentation system

ICAO: Expression for: wide area augmentation system (WAAS)

  • abbreviation: SBAS
“Say again”

An expression used to request a repetition of the last transmission.

Fr: « Répétez »

“Say altitude”

An expression used by ATC to ascertain an aircraft’s specific altitude or flight level (FL).

Fr: « Dites altitude »


ICAO: Abbreviation for: satellite-based augmentation system



Abbreviation for: Southern Control Area



Abbreviation for: special Category I



Abbreviation for: simultaneous converging instrument approaches



Abbreviation for: Southern Domestic Airspace


sea clutter

Radar echoes caused by waves of the sea.

Fr: échos de vagues

search and rescue

The use of aircraft, surface craft, submarines, and specialized rescue teams and equipment to search for and rescue personnel in distress on land or at sea.

  • abbreviation: SAR

Fr: recherches et sauvetage

secondary radar

Other expression for: secondary surveillance radar (SSR)

secondary surveillance radar

A radar system that requires complementary aircraft equipment (transponder). The transponder generates a coded reply signal in response to transmissions from the ground station (interrogator). Since this system relies on transponder-generated signals rather than signals reflected from the aircraft, as in primary surveillance radar, it offers significant operational advantages such as increased range and positive identification. 

  • abbreviation: SSR
  • also called: secondary radar
  • see also: radar

Fr: radar secondaire de surveillance

sectional chart

U.S.: Expression for: VFR navigation chart (VNC)


A part of an ATC unit that has a designated area of responsibility (AOR) in which ATS are provided.

Fr: secteur

see and avoid

An expression relating to a concept whereby pilots of aircraft flying in visual meteorological conditions (VMC), regardless of the type of flight plan (FP), are responsible for observing the presence of other aircraft, terrain and obstacles and of manoeuvring their aircraft as required to avoid these objects.

Fr: voir et éviter


Abbreviation for: selective calling system


selective calling system

A system that provides an automatic and selective method of calling any aircraft. Voice calling is replaced by the transmission of code tones to the aircraft over the international radiotelephony channels. This system is installed on all international frequencies at Canadian stations.

  • abbreviation: SELCAL

Fr: système d’appel sélectif


The spacing between aircraft, altitudes, or tracks.

Fr: espacement

separation minimum

The least allowable amount of lateral, longitudinal, or vertical separation to be applied.

Fr: minimum d’espacement

severe icing

An atmospheric condition in which the rate of ice accumulation is such that de-icing or anti-icing equipment cannot reduce or control the hazard.

Fr: givrage fort
severe turbulence

Turbulence that causes large, abrupt changes in altitude or attitude. It usually causes large variations in indicated airspeed (IAS). Aircraft may be momentarily out of control.

Fr: turbulence forte
severe weather forecast alert

U.S.: Preliminary messages issued in order to alert users that a severe weather watch bulletin (WW) is being issued. These messages define areas of possible severe thunderstorms or tornado activity.

  • abbreviation: AWW

Abbreviation for: simulated flameout



Abbreviation for: super high frequency


shock wave

A region of abrupt change in pressure and density moving ahead of the aircraft as a wave front at or above the speed of sound.

Fr: onde de choc

short-range clearance

U.S.: A clearance issued to a departing IFR flight which authorizes IFR flight to a specific fix short of the destination while ATC facilities are coordinating and obtaining the complete clearance.

Note: This procedure is not used in Canada.

short takeoff and landing aircraft

An aircraft that, at some weight within its approved operating weight, is capable of operating from a STOL runway in compliance with the applicable STOL characteristics and airworthiness, operations, noise, and pollution standards.

  • also called: STOL aircraft

Fr: aéronef à décollage et atterrissage courts

show line

Other expression for: flight line (2)

shuttle procedure

A manoeuvre involving a descent or a climb in a pattern resembling a holding pattern.

Fr: procédure de navette


Abbreviation for: standard instrument departure


sidestep maneuver [sic]

U.S.: A visual maneuver [sic] accomplished by a pilot at the completion of an instrument approach to permit a straight-in landing on a parallel runway not more than 1200 ft to either side of the runway to which the instrument approach was conducted.


Abbreviation for: significant meteorological information


significant meteorological information

Meteorological information issued concerning weather significant to the safety of aircraft. SIGMET advisories include the following:

(a) active thunderstorm areas or lines of thunderstorms;

(b) hurricanes, tropical storms;

(c) moderate hail;

(d) severe turbulence;

(e) severe icing;

(f) marked mountain waves;

(g) widespread sandstorms and dust storms;

(h) volcanic ash;

(i) severe squall lines;

(j) low-level wind shear; and

(k) tornadoes or waterspouts.

  • abbreviation: SIGMET

Fr: renseignements météorologiques significatifs

significant point

(1) An expression used to describe a NAVAID, a fix derived from a NAVAID, or a geographical location as expressed in latitude and longitude.

Fr: point significatif

(2) ICAO: A specified geographical location used in defining an ATS route or the flight path of an aircraft and for other navigation and ATS purposes.

Fr: point significatif

simulated approach

An instrument approach procedure (IAP) conducted in visual meteorological conditions (VMC) by an aircraft not on an IFR clearance.

  • also called: practice instrument approach

Fr: approche simulée

simulated flameout

A practice approach to a runway by a jet aircraft (normally military) at idle thrust. The approach may start at a relatively high altitude over a runway (high key) and may continue on a relatively high and wide downwind leg with a high rate of descent and a continuous turn to final.

  • abbreviation: SFO

Fr: arrêt simulé de turbomoteur

simultaneous converging instrument approaches

A procedure for conducting two or more simultaneous instrument approaches to converging runways.

  • abbreviation: SCIA

Fr: approches aux instruments simultanées convergentes

simultaneous ILS/MLS approach procedures

Approach procedures permitting instrument landing system (ILS) and microwave landing system (MLS) approaches to be conducted simultaneously at airports having parallel runways.

Fr: procédures d’approche ILS/MLS simultanées

Simultaneous Intersecting Runway Operations

Canada: Former term for: Land and Hold Short Operations (LAHSO)

  • abbreviation: SIRO

Fr: utilisation simultanée de pistes sécantes

Simultaneous Operations on Parallel or Near-Parallel Instrument Runways

A term used by ICAO to refer to operations in which aircraft conduct simultaneous approaches and/or departures from parallel or near-parallel instrument runways.

Note: Although the term “Simultaneous Operations on Parallel or Near-Parallel Instrument Runways” is not used in the U.S. or Canada, these operations are.

Fr: opérations simultanées sur pistes aux instruments parallèles ou quasi parallèles


Canada: Abbreviation for: Simultaneous Intersecting Runway Operations



ICAO: Abbreviation for: Simultaneous Operations on Parallel or Near-Parallel Instrument Runways


sonic flight

Flight at the speed of Mach 1.

Fr: vol sonique

Southern Control Area

A controlled airspace within the Southern Domestic Airspace (SDA) at 18 000 ft ASL and above.

  • abbreviation: SCA

Fr: région de contrôle du Sud

Southern Domestic Airspace

As geographically delineated in the Designated Airspace Handbook (DAH), all airspace within the Canadian Domestic Airspace (CDA) commencing at the Canada-United States border and extending northward to the southern limit of the Northern Domestic Airspace (NDA).

  • abbreviation: SDA

Fr: espace aérien intérieur du Sud


Abbreviation for: special aerospace defence exercise


special aerospace defence exercise

The flight of one or more military aircraft on a NOPAR (do not pass to air defence radar) IFR flight plan (FP) to conduct a test of the aerospace surveillance, detection and identification capability. If identification by interception of these aircraft is also planned, it shall be contingent upon the approval of a prearranged altitude reservation prior to takeoff.

Fr: exercice spécial de défense aérienne

special air-report

Special observations made by aircraft operating on international air routes whenever

(a) severe turbulence or severe icing is encountered;

(b) moderate turbulence, hail or cumulonimbus clouds are encountered during transonic or supersonic flight; or

(c) other meteorological conditions, for example, the other en route weather phenomena specified for SIGMET messages, are encountered

that, in the opinion of the pilot-in-command, may affect the safety or markedly affect the efficiency of other aircraft operations.
  • abbreviation: ARS

Fr: compte rendu en vol spécial

special aviation event

An air show, low-level air race, aerobatic competition, fly-in or balloon festival.

Fr: manifestation aéronautique spéciale

special Category I

The implementation of local area differential global positioning system (GPS) to provide early satellite navigation precision approach CAT I capability. Standards in Radio Technical Commission for Aeronautics (RTCA) DO 217 provide for certification of the ground station, data link and airborne receiver as a total system. The total system approval is unique to a given runway.

  • abbreviation: SCAT I

Fr: catégorie I spéciale

special emergency

U.S.: Expression for: acts of unlawful interference

special-use airspace

Airspace classified as:

(a) Class F advisory (CYA), Class F restricted (CYR) or Class F danger (CYD), which can be controlled airspace, uncontrolled airspace or a combination of both;

(b) military operations area (MOA), (below FL180 in the U.S.);

(c) ATC-assigned airspace (Military Area) (ATCAA) (FL180 and above in the U.S.);

(d) airspace restricted by NOTAM for forest fire aircraft operating restrictions; and

(e) other airspace restricted by NOTAM to cover specific situations such as oil-well fires, disaster areas, etc.

  • abbreviation: SUA

Fr: espace aérien à usage spécial

special VFR flight

A visual flight authorized by an ATC unit to operate within a control zone (CZ) under meteorological conditions that are below visual meteorological conditions (VMC).

  • abbreviation: SVFR

Fr: vol VFR spécial

speed adjustment

An ATC procedure used to request pilots to adjust aircraft speed to a specific value to provide the desired separation.

Fr: réglage de la vitesse

speed brake

Movable aerodynamic devices on aircraft that reduce indicated airspeed.

  • also called: dive brake

Fr: aérofrein


The person or agency responsible for the organization and conduct of a special aviation event.

Fr: organisateur

squawk (to)

To activate a specific mode, code or function on an aircraft transponder.

Fr: afficher

“Squawk ident”

A request for a pilot to activate the aircraft transponder identification feature.

Fr: « Affichez ident »


Abbreviation for: secondary surveillance radar


SSR code

A four-digit octal number received from the aircraft transponder when it is interrogated by a secondary surveillance radar (SSR).

Fr: code SSR

SSR mode

A letter or number assigned to a specific pulse spacing of the interrogation signals transmitted by an interrogator.

  • also called: mode

Fr: mode SSR


Other expression for: holding stack

standard altimeter setting

A pressure setting of 29.92 in. that, when set on the subscale of the sensitive altimeter, will cause the altimeter to read zero when at mean sea level.

Fr: calage altimétrique standard

standard instrument departure

An IFR ATC departure procedure published in the Canada Air Pilot (CAP) for pilot and controller use. SIDs may be either

(a) pilot navigation SIDs: SIDs where the pilot is required to use the applicable SID chart as reference for navigation to the en route phase; or

(b) vector SIDs: SIDs established where ATC will provide radar navigational guidance to a filed or assigned route, or to a fix depicted on the applicable SID chart. Pilots are expected to use the SID chart as a reference for navigation until the vector is commenced.

  • abbreviation: SID

Fr: départ normalisé aux instruments

standard instrument departure chart

An aeronautical chart designed to expedite clearance delivery and to facilitate transition between takeoff and en route operations. Each standard instrument departure (SID) procedure is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.

Fr: carte de départ normalisé aux instruments

standard pressure region

All Canadian Domestic Airspace (CDA) that is not designated as the altimeter setting region.

Fr: région d’utilisation de la pression standard

standard terminal arrival

An IFR ATC arrival procedure published in the Canada Air Pilot (CAP) for pilot and controller use.

  • abbreviation: STAR

Fr: arrivée normalisée en région terminale

standard terminal arrival chart

An aeronautical chart designed to expedite ATC arrival procedures and to facilitate transition between en route and instrument approach operations. Each standard terminal arrival (STAR) procedure is presented as a separate chart and may serve a single airport or more than one airport in a given geographical location.

Fr: carte d’arrivée normalisée en région terminale


An expression used in radiocommunication meaning “Wait and I will call you.”

Note: The caller would normally re-establish contact if the delay is lengthy. “Standby” is not an approval or denial.

Fr: « Attendez »


Abbreviation for: standard terminal arrival


State aircraft

(1) Canada: An aircraft owned by and used exclusively in the service of a government in Canada or a foreign state.

Fr: aéronef d’État

(2) ICAO: An aircraft used for military, customs, police or other law enforcement services of a State.

Fr: aéronef d’État


One or more transmitters or receivers, or a combination of transmitters and receivers, including the accessory equipment, necessary at one location for carrying on a radiocommunication service.

Fr: station

stepdown fix

A fix permitting additional descent within a segment of an instrument approach procedure (IAP) by identifying the point at which a controlling obstacle has been safely overflown.

Fr: repère de descente par paliers

STOL aircraft

Other expression for: short takeoff and landing aircraft


A procedure in which an aircraft lands, makes a complete stop on the runway, and then commences a takeoff from that point.

Fr: arrêt-décollé

“Stop buzzer”

An expression used in a situation where electronic countermeasures (ECM) should only be stopped when radar is essential to cope with traffic, and interference is such that it creates an emergency flight-safety situation.

Fr: « Arrêtez l’avertisseur »

stopover flight plan

A flight-plan format that, in a single submission, permits the filing of a sequence of VFR flights through interim full-stop destinations to a final destination.

Fr: plan de vol avec escales

“Stop squawk”

An expression used by ATC to tell the pilot to turn off the specified mode, code or function of the aircraft transponder.

Fr: « Cessez d’afficher »


A defined rectangular area on the ground at the end of the runway in the direction of takeoff prepared as a suitable area in which an aeroplane can be stopped in the case of an aborted takeoff.

Fr: prolongement d’arrêt

straight-in approach

(1) A VFR approach in which the aircraft enters the aerodrome traffic circuit on the final leg without having executed any other part of the circuit.

Fr: approche directe

(2) An IFR approach in which the aircraft begins the final approach without first having executed a procedure turn (PT).

Fr: approche directe

structured airspace

Certain portions of domestic airspace that will be structured for one-way traffic during times of peak traffic. Flight levels (FL) that are inappropriate for the direction of flight may be assigned to this traffic.

Fr: espace aérien structuré


Abbreviation for: special-use airspace



Abbreviation for: air sovereignty test


subsonic flight

Flight at a speed lower than Mach 1.

Fr: vol subsonique

super high frequency

The frequency band between 3 and 30 GHz.

  • abbreviation: SHF

Fr: fréquence supérieure

supersonic flight

Flight at a speed above Mach 1.

Fr: vol supersonique

surface weather observation

An aviation weather report describing the weather conditions at a specified location and at a specified time, as observed from the ground. Regular observations are made on the hour, and special observations are made as necessary to report a significant change in the weather.

Fr: observations météorologiques de surface

surveillance approach

(1) An emergency radar approach provided by ATC intended to assist an aircraft in executing an approach and landing.

Fr: approche au radar de surveillance

(2) U.S. Military: An instrument approach wherein the air traffic controller issues instructions, for pilot compliance, based on aircraft position in relation to the final approach course (azimuth) and the distance (range) from the end of the runway as displayed on the controller’s radar scope. The controller will provide recommended altitudes on the final approach if requested by the pilot.

surveillance radar

Radar equipment used to determine the position of an aircraft in range and azimuth.

Fr: radar de surveillance

survival ELT

An ELT that is removable from an aircraft, stowed so as to facilitate its ready use in an emergency and activated by survivors. Automatic activation may apply.

Fr: ELT de survie


Abbreviation for: special VFR flight

Date modified: