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Glossary - A B C
D E F G
H I J L
M N O P
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Term |
Definition |
Above
Ground Level (AGL) Altitude |
Altitude expressed in feet
measured above ground level. |
Accretion |
The growth of ice on aircraft surfaces in flight as a result of the collision with supercooled liquid water cloud droplets. |
Active Frost |
Frost that actively grows in mass and thickness. This phenomenon occurs when aircraft surfaces are at or below freezing (0ºC) AND at or below dew point. |
Aerodynamic Acceptance Test |
Laboratory test that establish if deicing and anti-icing fluids meet flow off requirements during takeoff ground acceleration and climb. |
Aeronautical
Information Manual (AIM) |
A primary FAA publication
whose purpose is to instruct airmen about operating in the
National Airspace System of the U.S. It provides basic flight
information, ATC Procedures and general instructional information
concerning health, medical facts, factors affecting flight
safety, accident and hazard reporting, and types of aeronautical
charts and their use. |
Air mass |
A widespread body of air in which its homogeneous properties were established while that air was over a particular region of the earth's surface and that undergoes specific modifications while moving away from its source region. |
Air Operator |
The holder of an air operator certificate. |
Air Operator Certificate |
A certificate issued under the CARs that authorizes the holder of the certificate to operate a commercial air service. |
Aircraft Deicing Facility |
A facility where:
•
frost, snow or ice are removed (deicing) from an aircraft in order to provide clean surfaces; and/or
•
Critical surfaces of the aircraft receive protection (anti-icing) against the formation of frost or ice, or the accumulation of snow or slush for a limited period of time.
• Fluid Storage, Equipment Maintenance, Environmental Mitigation, Control Centre programs are in place. |
Aircraft Deicing Pad |
A designated area on an aircraft deicing facility intended to be used for parking an aircraft to conduct deicing or anti-icing activities, consisting of an inner area for the parking of an aircraft to receive deicing/anti-icing treatment. On a centralized deicing facility, the aircraft deicing pad also includes an outer area for maneuvering deicing vehicles (safe zone). The outer area provides the vehicle lane width necessary for deicing vehicles to safely perform during the deicing operation. |
AIRMET |
In-flight weather advisories
issued only to amend the area forecast concerning weather
phenomena that are of operational interest to all aircraft
and potentially hazardous to aircraft having limited capability
because of lack of equipment, instrumentation, or pilot qualifications.
AIRMETs concern weather of less severity than that covered
by SIGMETs or Convective SIGMETs. AIRMETs cover moderate icing,
moderate turbulence, sustained winds of 30 knots or more at
the surface, widespread areas of ceilings less than 1,000
feet and/or visibility less than 3 miles, and extensive mountain
obscurement. |
Airspeed |
The speed of an aircraft
relative to its surrounding air mass. The unqualified term
"airspeed" means one of the following: Indicated
Airspeed- The speed shown on the aircraft airspeed indicator.
This is the speed used in pilot/controller communications
under the general term "airspeed." True Airspeed-
The airspeed of an aircraft relative to undisturbed air. Used
primarily in flight planning and en route portion of flight.
When used in pilot/controller communications, it is referred
to as "true airspeed" and not shortened to "airspeed." |
Altitude |
The height of a level, point,
or object measured in feet Above Ground Level (AGL) or from
Mean Sea Level (MSL.) AGL Altitude- Altitude expressed in
feet measured above ground level. MSL Altitude- Altitude expressed
in feet measured from mean sea level. Indicated Altitude-
The altitude as shown by an altimeter. On a pressure or barometric
altimeter it is altitude as shown uncorrected for instrument
error and uncompensated for variation from standard atmospheric
conditions. |
Anti-icing |
A precautionary procedure that provides protection against the formation of frost and/or ice and the accumulation of slush and/or snow on treated surfaces of an aircraft for a period of time during active frost, frozen precipitation, and freezing precipitation.
The application of a freezing point depressant to a surface either following deicing or in anticipation of subsequent winter precipitation is intended to protect the critical surfaces from ice adherence for a limited period of time. The fluid is capable of absorbing freezing or frozen precipitation until the fluid freezing point coincides with the ambient temperature. Once this fluid freezing point has been reached, the fluid is no longer capable of protecting the aircraft from ground icing conditions. |
Anti-icing Fluid |
1. type I fluid;
2. mixture of water and type I fluid;
3. type II fluid or type IV fluid;
4. mixture of water and type II or type IV fluid.
NOTE: Anti-icing fluid is normally applied unheated on clean aircraft surfaces, but may be applied heated. |
Approach
Clearance |
Authorization by ATC for
a pilot to conduct an instrument approach. The type of instrument
approach for which a clearance and other pertinent information
is provided in the approach clearance when required. |
Approach
Speed |
The recommended speed contained
in aircraft manuals used by pilots when making an approach
to landing. This speed will vary for different segments of
an approach as well as for aircraft weight and configuration. |
Apron |
That part of an aerodrome, other than the maneuvering area, intended to accommodate the loading and unloading of passengers and cargo, the refueling, servicing, maintenance and parking of aircraft, and any movement of aircraft, vehicles and pedestrians necessary for such purposes. |
Automated Surface Observation System (ASOS) / Automated Weather Observation System (AWOS) |
A suite of sensors which measure, collect, and disseminate weather data to help meteorologists, pilots, and flight dispatchers prepare and monitor weather forecasts, plan flight routes, and provide necessary information for correct takeoffs and landings. The basic difference between these two automated weather systems is that the ASOS is comprised of a standard suite of weather sensors and is a product of a National Weather Service (NWS), Department of Defense (DoD), and Federal Aviation Administration (FAA) joint venture. The AWOS is a suite of weather sensors of many different configurations that are procured by the FAA or purchased by individuals, groups, airports, etc. |
Automatic
Terminal Information Service (ATIS) |
The continuous broadcast
of recorded noncontrol information in selected terminal areas.
Its purpose is to improve controller effectiveness and to
relieve frequency congestion by automating the repetitive
transmission of essential but routine information; e.g., "Los
Angeles information Alfa. One three zero zero Coordinated
Universal Time. Weather, measured ceiling two thousand overcast,
visibility three, haze, smoke, temperature seven one, dew
point five seven, wind two five zero at five, altimeter two
niner niner six. I-L-S Runway Two Five Left approach in use,
Runway Two Five Right closed, advise you have Alfa." |
Aviation Weather Service Program |
Aviation weather service provided by the National Weather Service (NWS) and the Federal Aviation Administration (FAA) that collects and disseminates pertinent weather information for pilots, aircraft operators, and ATC. Available aviation weather reports and forecasts are displayed at NWS offices and FAA Flight Service Stations (FSS). |
Below
Minimums |
Weather conditions below
the minimums prescribed by regulation for the particular action
involved (e.g., landing minimums, takeoff minimums). |
Braking
Action |
A report of conditions on
the airport movement area providing a pilot with a degree/quality
of braking that might be expected. Braking action is reported
in terms of good, fair, poor, or nil. |
Braking
Action Advisories |
When tower controllers have
received runway braking action reports which include the terms
"poor" or "nil," or whenever weather conditions
are conducive to deteriorating or rapidly changing runway
braking conditions, the tower will include on the ATIS broadcast
the statement, "BRAKING ACTION ADVISORIES ARE IN EFFECT."
During the time Braking Action Advisories are in effect, ATC
will issue the latest braking action report for the runway
in use to each arriving and departing aircraft. Pilots should
be prepared for deteriorating braking conditions and should
request current runway condition information if not volunteered
by controllers. Pilots should also be prepared to provide
a descriptive runway condition report to controllers after
landing. |
Carburetor
Ice |
Ice formed in the carburetor
due to the effects of lowered temperature by decreased air
pressure and fuel vaporization in the presence of significant
water vapor (high humidity). Note that carburetor ice rarely
occurs in a low humidity environment, e.g., winter months
in the northern part of the country. |
Ceiling |
The heights above the earth's
surface of the lowest layer of clouds or obscuring phenomena
that is reported as "broken," "overcast,"
or "obscuration," and not classified as "thin"
or "partial." |
Celsius |
A temperature scale where
0 is the freezing point of water and 100 is the boiling point
of water. To convert Celsius to Fahrenheit: F = (9/5)*C +
32. |
Center
Weather Advisory (CWA) |
An unscheduled weather advisory
issued by Center Weather Service Unit meteorologists for ATC
use to alert pilots of existing or anticipated adverse weather
conditions within the next 2 hours. A CWA may modify or redefine
a SIGMET. |
Central Deicing Facility (CDF) |
A Transport Canada approved facility at an airport for the purpose of conducting deicing and anti-icing operations. |
Charts |
A map used in air navigation
containing all or part of the following: topographic features,
hazards and obstructions, navigation aids, navigation routes,
designated airspace, and airports. For specifics on some commonly
used aeronautical charts see: Sectional Aeronautical Charts,
VFR Terminal Area Charts, World Aeronautical Charts, En Route
Low Altitude Charts, En Route High Altitude Charts, Instrument
Approach Procedures, Instrument Departure Procedures, and
Standard Terminal Arrival Charts. |
Check |
An examination of an item against a relevant standard by a trained and qualified person. |
Clean Aircraft Concept |
When conditions exist during ground operations that are conducive to aircraft icing, no person shall conduct or attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its critical surfaces. |
Clear
(or Glaze) Ice |
Clear ice is also called
glaze ice. This ice type appears lumpy and translucent or
clear and smooth. It results from supercooled liquid water
droplets striking the surface but not freezing immediately
upon contact. Clear ice tends to form horns or other complex
shapes which can significantly disrupt the airflow. |
Climbout |
That portion of flight operation
between takeoff and the initial cruising altitude. |
Cloud |
A cloud is a visible accumulation
of minute water droplets and/or ice particles in the atmosphere
above the Earth's surface. Cloud differs from ground fog,
fog, or ice fog only in that the latter are, by definition,
in contact with the Earth's surface. |
Collision-Coalescence |
The theory of large cloud
droplet formation in which smaller droplets continue to collide
and join together until a significantly larger droplet is
formed. |
Cold-soak Effect |
The wings of aircraft are said to be “cold-soaked” when they contain very cold fuel as a result of having just landed after a flight at high altitude or from having been re-fuelled with very cold fuel. Whenever precipitation falls on a cold-soaked aircraft when on the ground, clear icing may occur. Even in ambient temperatures between -2°C and +15°C, ice or frost can form in the presence of visible moisture or high humidity if the aircraft structure remains at 0°C or below. Clear ice is very difficult to be detected visually and may break loose during or after takeoff. The following factors contribute to cold-soaking: temperature and quantity of fuel in fuel cells, type and location of fuel cells, length of time at high altitude flights, temperature of re-fuelled fuel and time since re-fuelling. |
Cold Soaking |
Ice can form even when the outside air temperature (OAT) is well above 0°C (32°F). An aircraft equipped with wing fuel tanks may have fuel that is at a sufficiently low temperature such that it lowers the wing skin temperature to below the freezing point of water. If an aircraft has been at a high altitude, where cold temperature prevails, for a period of time, the aircrafts’ major structural components such as the wing, tail and fuselage will assume the lower temperature, which will often be below the freezing point. This phenomenon is known as cold soaking. While on the ground, the cold soaked aircraft will cause ice to form when liquid water, either as condensation from the atmosphere or as rain, comes in contact with critical surfaces. |
Contaminated
Runway |
A runway is considered contaminated
whenever standing water, ice, snow, slush, frost in any form,
heavy rubber, or other substances are present. A runway is
contaminated with respect to rubber deposits or other friction-degrading
substances when the average friction value for any 500-foot
segment of the runway within the ALD fails below the recommended
minimum friction level and the average friction value in the
adjacent 500-foot segments falls below the maintenance planning
friction level. |
Contamination |
Any frost, ice, slush or snow that adheres to the critical surfaces of an aircraft. |
Contamination Check |
Check of aircraft surfaces for contamination to establish the need for de-icing. |
Convective
SIGMET |
A weather advisory concerning
convective weather significant to the safety of all aircraft.
Convective SIGMETs are issued for tornadoes, lines of thunderstorms,
embedded thunderstorms of any intensity level, areas of thunderstorms
greater than or equal to VIP level 4 with an area coverage
of 4/10 (40%) or more, and hail 3/4 inch or greater. |
Coordinated
Universal Time (UTC) |
Formerly Greenwich Mean
Time, also known as Z or ZULU time, UTC is the international
time standard. |
Critical Surfaces |
The wings, control surfaces, rotors, propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing surface on an aircraft and, in the case of an aircraft that has rear-mounted engines, includes the upper surface of its fuselage. |
Critical Surface Inspection |
A critical surface inspection is a pre-flight external inspection of critical surfaces conducted by a qualified person as specified in CAR Part VI, subsection 602.11(5), to determine if they are contaminated by frost, ice, snow or slush. This inspection is mandatory whenever ground icing conditions exist and, if the aircraft is deiced / anti-iced with fluid, must take place immediately after the final, application of fluid or where an approved alternative method of deicing is used, upon completion of this process. After the inspection, a report completed by a qualified individual must be submitted to the pilot-in-command. |
Critical Surface Inspection Report |
This report must be made to the pilot-in-command and, if applicable, state the time at which the last full application of deicing or anti-icing fluid began, the type of fluid used, the ratio of the fluid mixture. Should the standard documented method not be used, the sequence in which the critical surfaces were de-iced or anti-iced must be stated. In addition, the report must confirm that all critical surfaces are free of contamination. |
Cumuliform
or Cumulous Clouds |
The theory of large cloud
droplet formation in which smaller droplets continue to collide
and join together until a significantly larger droplet is
formed. |
Return
to Top |
Defrosting |
The forms of ice protection that remove existing accreted ice from aircraft surfaces, such as pneumatic boots. Compare to anti-icing. |
Deicing |
Deicing is a procedure by which frost, ice, slush or snow is removed from an aircraft to render it free of contamination.
Deicing is a general term for the removal of ice, snow, slush or frost from an aircraft’s critical surfaces, by mechanical means, by the use of heat, or by the use of a heated fluid or a combination thereof. When frost, snow or ice is adhering to a surface, the surface must be heated and fluid pressure used to remove the contaminant. |
Deicing Fluid |
a) heated water;
b) type I fluid;
c) mixture of water and type I fluid;
d) type II or type IV fluid;
e) mixture of water and type II or type IV fluid.
NOTE: De-icing fluid is normally applied heated in order to assure maximum efficiency. |
Deicing Operator |
The organization providing de/anti-icing related services to air operators at a given location. The Deicing Operator may be a qualified third party, another airline, or the Air Operator. The Deicing Operator must provide a service in accordance with the air operator’s approved ground icing program, where such a program exists. |
Deposition |
A process where water vapor turns directly to ice upon contact with a surface, and does not pass through a liquid state. |
Deviations |
A departure from a current
clearance, such as an off course maneuver to avoid weather
or turbulence. Where specifically authorized in the FARs and
requested by the pilot, ATC may permit pilots to deviate from
certain regulations. |
Dew
Point |
The temperature at which
water vapor will begin to condense. The relative humidity
at the dew point is 100 percent. |
Direct
User Access Terminal (DUAT) |
A computer terminal where
pilots can directly access meteorologic and aeronautical information,
plus file a flight plan without the assistance of an FSS. |
Emergency |
A distress or an urgency
condition. |
En
Route High Altitude Charts |
Provide aeronautical information
for en route instrument navigation (IFR) in the high altitude
stratum. Information includes the portrayal of jet routes,
identification and frequencies of radio aids, selected airports,
distances, time zones, special use airspace, and related information. |
En
Route Low Altitude Charts |
Provide aeronautical information
for en route instrument navigation (IFR) in the low altitude
stratum. Information includes the portrayal of airways, limits
of controlled airspace, position identification and frequencies
of radio aids, selected airports, minimum en route and minimum
obstruction clearance altitudes, airway distances, reporting
points, restricted areas, and related data. Area charts, which
are a part of this series, furnish terminal data at a larger
scale in congested areas. |
Fahrenheit |
A temperature scale where
32 degrees is the freezing point of water and 212 degrees
is the boiling point of water. To convert Fahrenheit to Celsius:
C = (5/9) * (F - 32). |
Final
Approach |
That part of an instrument
approach procedure which commences at the specified final
approach fix or point, or where such a fix or point is not
specified, at the end of the last procedure turn, base turn
or inbound turn of a racetrack procedure, if specified; or
at the point of interception of the last track specified in
the approach procedure; and ends at a point in the vicinity
of an aerodrome from which a landing can be made; or a missed
approach procedure is initiated. |
Fix |
A geographical position
determined by visual reference to the surface, by reference
to one or more radio NAVAIDs, by celestial plotting, or by
another navigational device. |
Flameout |
An emergency condition caused
by the complete loss of turbine engine power. |
Flight
Level |
Altitudes flown with the
altimeter set to 29.92 inches Hg. Each is stated in three
digits that represent hundreds of feet. For example, flight
level (FL) 250 represents a barometric altimeter indication
of 25,000 feet; FL 255, an indication of 25,500 feet. |
Flight
Service Station (FSS) |
Air traffic facilities which
provide pilot briefing, en route communications and VFR search
and rescue services, assist lost aircraft and aircraft in
emergency situations, relay ATC clearances, originate Notices
to Airmen, broadcast aviation weather and NAS information,
receive and process IFR flight plans, and monitor NAVAIDs.
In addition, at selected locations, FSSs provide En Route
Flight Advisory Service (Flight Watch), take weather observations,
issue airport advisories, and advise Customs and Immigration
of transborder flights. |
Fluid Deicing/Anti-icing Methods |
These are methods of using acceptable fluids for the removal of frozen contamination from an aircraft’s critical surfaces and then for preventing the formation and/or accumulation of contamination on an aircraft for a limited period of time. The details are contained in The Society of Automotive Engineers (SAE) document ARP4737, entitled: “Aircraft deicing/anti-icing Methods”. |
Fluid Dryout |
Fluid residue that may remain in aerodynamically quiet areas throughout a flight. |
Fluid Endurance Time |
Endurance times of anti-icing fluids are measured in laboratory and field tests under specific contamination and temperature conditions using flat test plates in accordance with the SAE documents AMS 1424 & AMS 1428. These tests are considered to replicate the failure of fluid during aircraft operations.
Fluid Failure.
Typically, in the case of snow, a layer of snow eventually accumulates on the surface of the fluid and is no longer being absorbed by the fluid. The appearance of a build up becomes evident. There is a distinct loss of shine or gloss on the surface of the fluid. |
Fluid Failure |
Typically, in the case of snow, a layer of snow eventually accumulates on the surface of the fluid and is no longer being absorbed by the fluid. The appearance of a build up becomes evident. There is a distinct loss of shine or gloss on the surface of the fluid. In the case of freezing precipitation, usually only a reduction in shine or gloss on the surface results, and it is particularly difficult to detect. |
Forced Air Deicing Method |
This is a method of deicing using a concentrated flow of air under pressure to remove
contamination from an aircraft, which may be used in conjunction with deicing fluids. |
Foreign Object Damage (FOD) |
Term used to describe damage done to an aircraft due to collision with small foreign objects. |
Freezing Drizzle |
Fairly uniform precipitation composed exclusively of fine drops (diameter less than 0.5 mm [0.02in]) very close together which freezes upon impact with the ground or other exposed objects. |
Freezing Fog |
A suspension of numerous minute water droplets which freezes upon impact with ground or other exposed objects, generally reducing the horizontal visibility at the earth's surface to less than 1 km (5/8 mile). |
Freezing
Level |
As used in aviation forecasts,
the altitude (in feet MSL) at which water freezes. |
Freezing Rain |
Droplets of rain that freeze immediately on contact with structures or vehicles. |
Freezing Point Depressant (FPD) Fluids |
The generic term applied to all types of deicing fluids. |
Front |
A boundary between air masses
of different temperatures and moisture. |
Frost/Hoar Frost |
Ice crystals that form from ice saturated air saturated with vapor at temperatures below 0°C (32°F) by direct sublimationdeposition on the ground or other exposed objects. |
Frozen Contaminants |
Frozen contaminants include light freezing rain, freezing rain, freezing drizzle, frost, ice, ice pellets, snow, snow grains, and slush. |
Fuel
Remaining |
A phrase used by either
pilots or controllers when relating to the fuel remaining
on board until actual fuel exhaustion. When transmitting such
information in response to either a controller question or
pilot initiated cautionary advisory to air traffic control,
pilots will state the APPROXIMATE NUMBER OF MINUTES the flight
can continue with the fuel remaining. All reserve fuel SHOULD
BE INCLUDED in the time stated, as should an allowance for
established fuel gauge system error. |
Return
to Top |
Ground Ice Detection System (GIDS) |
A system designed to detect frozen contaminants on an aircraft. These systems can be either ground based or aircraft based systems. GIDS may be either a spot sensor or an area sensor system. If approved by Transport Canada, such a system may be used as an alternative to other inspection methods. |
Ground
Icing |
Structural icing that occurs
on an aircraft on the ground, usually produced by snow or
frost. |
Ground Icing Conditions |
With due regard to aircraft skin temperature and weather conditions, ground icing conditions exist when frost, ice, or snow is adhering or may adhere to the critical surfaces of an aircraft.
Ground Icing Conditions also exist when active frost, frozen or freezing precipitation is reported or observed. |
Ground Icing Operations Program |
A Ground Icing Operations Program consists of a set of procedures, guidelines, and processes, documented in manuals, which ensure that an Air Operator’s aircraft does not depart with frost, ice, snow or slush adhering to critical surfaces. This program is mandatory for CAR 705 operations and must be approved by Transport Canada. |
Ground
Speed |
The speed of an aircraft
relative to the surface of the earth. |
Hail |
Precipitation consisting of small balls or pieces of ice with a diameter ranging from 5 mm to greater than 50 mm falling either separately or agglomerated. |
High
(Pressure System) |
Area of high pressure completely
surrounded by lower pressure. |
High Humidity Endurance Test (HHET) |
A laboratory test that measures endurance time of anti-icing fluid under conditions of high humidity. This test is intended to simulate frost conditions. |
Hoarfrost |
A uniform, thin white deposit of fine crystalline texture that forms on exposed surfaces during calm, cloudless nights when the temperature falls below freezing and the humidity of the air at the surface is close to the saturation point. It is not associated with precipitation. The deposit is thin enough that the underlying surface features, such as paint lines, markings or lettering can be distinguished. |
Holdover Time (HOT) |
Holdover time is the estimated time that an application of anti-icing fluid is effective in preventing frost, ice, slush or snow from adhering to treated surfaces. Holdover time is calculated as the beginning with the final application of the anti-icing fluid, and as expiring when the fluid is no longer effective, as measured in endurance time tests and published in “Holdover Time Guidelines”. |
Hold Over Time Guidelines |
Holdover Time Tables are referred to as Holdover Time Guidelines because this term more appropriately represents their function in providing guidance to flight crew and the need for the flight crew to use judgment in their interpretation.
Fluid holdover times, as published by , Commercial and Business Aviation, Transport Canada are found published in “Holdover Time Guidelines” as tables and may be used either as guidelines or decision-making criteria in assessing whether it is safe to take off. When holdover times are used as decision-making criteria, only the lowest time value in a cell shall be used. The procedures to be followed after the holdover time has expired must be clearly documented. The use of holdover time guidelines is mandatory if they are part of the Air Operator’s approved ground icing program. |
Hold
Procedure |
A predetermined maneuver
that keeps aircraft within a specified airspace while awaiting
further clearance from air traffic control. Also used during
ground operations to keep aircraft within a specified area
or at a specified point while awaiting further clearance from
air traffic control. |
Holding
Fix |
A specified fix identifiable
to a pilot by NAVAIDs or visual reference to the ground used
as a reference point in establishing and maintaining the position
of an aircraft while holding. |
Horizontal
Extent |
The horizontal distance
of an icing encounter. Generally, icing encounters in stratus
clouds have a greater horizontal extent than in cumulous clouds. |
Ice |
The solid form of water. Clear Ice is often difficult to detect visually on an aircraft’s critical surfaces. It can be present in a transparent form, which may make the aircraft’s critical surfaces appear to be wet. |
Ice Bridging |
A myth for modern equipment. The concern was that ice would form a sheath at the inflated extent of the boot, and remain there. Subsequent boot cycles would be unable to remove this ice. Bridging may have occurred with very early boot technology that had wide tubes and slow inflation/deflation rates. However, there is no evidence that modern pneumatic boots have ever had this problem. |
Icehouse |
A specially equipped control center, located within a Central Deicing Facility, to control and monitor all operations associated with the facility. |
Ice Pellets |
These are a type of precipitation consisting of transparent or translucent pellets of ice, 5 mm or less in diameter.
They may be spherical, irregular, or (rarely) conical in shape. Ice pellets usually bounce when hitting hard ground, and make a sound upon impact. |
Ice
Protection Equipment |
Equipment used to remove
and/or prevent the accretion of ice on an aircraft. You are
guaranteed that the equipment has been demonstrated to provide
adequate ice protection only if the aircraft is certified
for flight into known icing conditions. Some ice protection
equipment has only been demonstrated to be airworthy and not
demonstrated to provide adequate ice protection. |
Icing
Intensity |
See Trace Icing, Light Icing,
Moderate Icing, or Severe Icing. |
Icing
Types |
See Clear (or glaze) Ice,
Mixed Ice, or Rime Ice. |
Indicated
Airspeed |
The speed shown on the aircraft
airspeed indicator. This is the speed used in pilot/controller
communications under the general term "airspeed." |
Indicated
Altitude |
The altitude as shown by
an altimeter. On a pressure or barometric altimeter it is
altitude as shown uncorrected for instrument error and uncompensated
for variation from standard atmospheric conditions. |
Infrared Heat Deicing Method |
A method of deicing using infrared (IR) thermal energy. |
Instrument
Approach Procedures (IAP) Charts |
Portray the aeronautical
data which is required to execute an instrument approach to
an airport. These charts depict the procedures, including
all related data, and the airport diagram. Each procedure
is designated for use with a specific type of electronic navigation
system including NDB, TACAN, VOR, ILS/MLS, and RNAV. These
charts are identified by the type of navigational aid(s) that
provide final approach guidance. |
Instrument
Departure Procedure (DP) Charts |
Designed to expedite clearance
delivery and to facilitate transition between takeoff and
en route operations. Each DP is presented as a separate chart
and may serve a single airport or more than one airport in
a given geographical location. |
Instrument
Flight Rules (IFR) |
FARs that govern flight
in instrument meteorologic conditions-flight by reference
to aircraft instruments. |
Instrument
Meteorological Conditions |
Meteorological conditions
expressed in terms of visibility, distance from cloud, and
ceiling less than the minima specified for visual meteorological
conditions. |
Intercycle
Ice |
Ice that consists of Residual
Ice, plus ice accreted between boot cycles. |
Inversion |
Atmospheric condition where
temperature increases with altitude. |
Return
to Top |
Jet
Stream |
A migrating stream of high-speed
winds present at high altitudes. |
Light Freezing Rain |
Precipitation of liquid water particles which freezes upon impact with the ground or other exposed objects, either in the form of drops of more than 0.5 mm (0.02 inch) or smaller drops which, in contrast to drizzle, are widely separated. Measured intensity of liquid water particles is up to 2.5 mm/hour (0.10 inch/hour) or 25 grams/dm2/hour with a maximum of 0.25 mm (0.01 inch) in 6 minutes. |
Light
Icing |
The rate of accumulation
may create a problem if flight is prolonged in this environment
(over 1 hour). Occasional use of deicing/anti-icing equipment
removes/prevents accumulation. |
Liquid
Water Content (LWC) |
The total mass of water
contained in all the liquid cloud droplets within a unit volume
of cloud. Units of LWC are usually grams of water per cubic
meter of air (g/m3). |
Low
(Pressure System) |
An area of low pressure
completely surrounded by higher pressure. |
Low-level
Wind Shear |
Wind shear that occurs within
2000 feet of the surface. |
Lowest Operational Use Temperature (LOUT) |
For a given fluid is the higher of the lowest temperature at which the fluid meets the aerodynamic acceptance test for a given aircraft type, or the actual freezing point of the fluid plus a freezing point buffer of 7°C for type I or 10°C for type II III & IV. |
Mean Sea Level (MSL) Altitude |
Altitude expressed in feet measured from mean sea level. |
Maneuvering Area |
That part of an aerodrome to be used for the take-off, landing and taxiing of aircraft, excluding aprons. |
Median
Volumetric Diameter (MVD) |
The droplet diameter that
divides the total amount of water in half; half the water
volume will be in larger droplets and half in smaller droplets. |
Micron |
One-millionth of a meter
or one-thousandth of a millimeter. |
Minimum
En Route IFR Altitude (MEA) |
The lowest published altitude
between radio fixes that assures acceptable navigational signal
coverage and meets obstacle clearance requirements between
those fixes. The MEA prescribed for a Federal airway or segment
thereof, area navigation low or high route, or other direct
route applies to the entire width of the airway, segment,
or route between the radio fixes defining the airway, segment,
or route. |
Minimums |
Minimum weather condition
requirements established for a particular operation or type
of operation (e.g., IFR takeoff or landing, alternate airport
for IFR flight plans, VFR flight, etc.). |
Missed
Approach |
A maneuver conducted by
a pilot when an instrument approach cannot be completed to
a landing. The route of flight and altitude are shown on instrument
approach procedure charts. A pilot executing a missed approach
prior to the Missed Approach Point (MAP) must continue along
the final approach to the MAP. The pilot may climb immediately
to the altitude specified in the missed approach procedure.
At locations where ATC radar service is provided, the pilot
should conform to radar vectors when provided by ATC in lieu
of the published missed approach procedure. |
Mixed
Ice |
The ice type that appears
clear near the stagnation line turning to white rime near
the edges. It occurs at conditions between those that form
pure clear and pure rime ice. Similar to clear ice, mixed
ice accretions can significantly disrupt airflow and cause
handling and performance problems. |
Mixed
Icing Conditions |
An atmospheric environment
where supercooled liquid water and ice crystals coexist. |
Moderate and Heavy Freezing Rain |
Precipitation of liquid water particles which freezes upon impact with the ground or other exposed objects, either in the form of drops of more than 0.5 mm (0.02 inch) or smaller drops which, in contrast to drizzle, are widely separated. Measured intensity of liquid water particles is more than 2.5 mm/hour (0.10 inch/hour) or 25 grams/dm2/hour. |
Moderate
Icing |
The rate of accumulation
is such that even short encounters become potentially hazardous
and use of deicing/anti-icing equipment or flight diversion
is necessary. |
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Notice
to Airmen (NOTAM) |
A notice containing information
(not known sufficiently in advance to publicize by other means)
concerning the establishment, condition, or change in any
component (facility, service, or procedure of, or hazard in
the National Airspace System) the timely knowledge of which
is essential to personnel concerned with flight operations. |
Obstacle |
An existing object, object
of natural growth, or terrain at a fixed geographical location
or which may be expected at a fixed location within a prescribed
area with reference to which vertical clearance is or must
be provided during flight operation. |
Occluded
Front |
Occur when an air mass is
trapped between two colder air masses and is forced to higher
altitudes. Occluded fronts may combine characteristics of
both warm and cold fronts. |
Orographic |
A term used to describe
the effects caused by terrain, especially mountains, on the
weather. An orographic effect is categorized as either an
upslope or a downslope. Air moving up a slope rises and tends
to cool; air moving down a slope sinks and tends to warm. |
Outside
Air Temperature (OAT) |
The air temperature indicated
by the aircraft's temperature probe. Depending upon the temperature
probe design, Outside Air Temperature (OAT) will be somewhere
in the range between the Static Air Temperature (SAT) and
the Total Air Temperature (TAT). Flight computers may correct
OAT to read either SAT or TAT. (see also Static Air Temperature
and Total Air Temperature). |
Pilot
Briefing |
A service provided by the
FSS to assist pilots in flight planning. Briefing items may
include weather information, NOTAMS, military activities,
flow control information, and other items as requested. |
Pilot-in-Command (PIC) |
The pilot responsible for
the operation and safety of an aircraft during flight time. |
Pilot Briefing |
A service provided by an FSS to assist pilots with flight planning. Briefing items may include weather information, notices to airmen (NOTAMs), military activities, flow control information, and other items, as requested. |
Pilot's
Discretion |
When used in conjunction
with altitude assignments, means that ATC has offered the
pilot the option of starting climb or descent whenever he
wishes and conducting the climb or descent at any rate he
wishes. He may temporarily level off at any intermediate altitude.
However, once he has vacated an altitude, he may not return
to that altitude. |
Pilot
Report (PIREP) |
A report of meteorological
phenomena encountered by aircraft in flight. |
Precipitation |
The rate at which precipitation is either measure or judge to be falling. Winter precipitation is a key factor in estimating the Holdover Time for an anti-icing fluid. It is the indication of moisture content. |
Precipitation Rate |
Any or all of the forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the ground. |
Pre-Takeoff Check |
A check, after deicing application, to ensure all aircraft surfaces are free of frozen contaminants. |
Pre-Takeoff Contamination Inspection |
An inspection conducted by a qualified person, immediately prior to take-off, to determine if an aircraft's critical surfaces are contaminated by frost, ice, slush or snow. This inspection is mandatory under some circumstances. |
Pre-Takeoff Contamination Inspection Report |
This report must be made to the pilot-in-command and, when a documented inspection method has not been used, must describe how the inspection was conducted. The report must also confirm that all critical surfaces are free of contamination. |
Relative
Humidity |
The ratio, expressed as
a percentage, of water vapor present compared with the maximum
amount possible at the present temperature. |
Representative Surface |
Surfaces which can be readily and clearly observed by flight crew during day and night operations, and which are suitable for judging whether or not critical surfaces are contaminated. Examination of one or more representative aircraft surfaces may be used for the Pre-Take-off Contamination Inspection, if a tactile examination is not required. Transport Canada must approve the use of these aircraft specific surfaces. |
Residual
Ice |
Ice that remains on the
boot immediately after a boot inflation and deflation. |
Rime
Ice |
The ice type that appears
rough, milky and opaque. Rime ice is formed by the instantaneous
freezing of supercooled droplets as they strike the aircraft. |
Runback |
Icing that occurs when liquid
water impacts an aircraft surface, flows aft past the impact
region, and then freezes. This can occur at near freezing
temperatures, with very high liquid water levels, or when
a thermal ice protection system doesn't evaporate the impacting
water. |
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Sectional
Aeronautical Charts |
(1:500,000) Designed for
visual navigation of slow or medium speed aircraft. Topographic
information on these charts features the portrayal of relief
and a judicious selection of visual checkpoints for VFR flight.
Aeronautical information includes visual and radio aids to
navigation, airports, controlled airspace, restricted areas,
obstructions, and related data. |
Service Provider |
The organization providing de/anti-icing related services to air operators at a given location. The Service Provider may be a qualified third party, another airline, or the Air Operator. The Service Provider must provide a service in accordance with the air operator’s approved ground icing program, where such a program exists. |
Severe
Icing |
The rate of accumulation
is such that deicing/anti-icing equipment fails to reduce
or control the hazard. Immediate flight diversion is necessary. |
SIGMET |
A SIGnificant METeorological
advisory that warns of phenomena that affect all aircraft.
SIGMET advisories cover severe and extreme turbulence, severe
icing, and widespread dust or sandstorms that reduce visibility
to less than 3 miles. |
Slush |
Snow that has a water content
exceeding its freely drained condition such that it takes
on fluid properties (e.g., flowing and splashing). |
Snow |
A porous, permeable aggregate
of ice grains that can be predominantly single crystals or
close groupings of several crystals. |
Snow Grains |
Precipitation that comprises very small white and opaque grains of ice. These grains are fairly flat or elongated; their diameter is less than 1 mm. When they hit hard ground, they do not bounce or shatter. |
Snow Pellets |
Precipitation which consists of white and opaque grains of ice. These grains are spherical or sometimes conical; their diameter is about 2-5 mm. Grains are brittle, easily crushed. They do bounce and break on hard ground. |
Stabilator |
A tail surface that acts
as both stabilizer and control surface. The moveable surface
can minimize the local angle of attack, so this form of tail
surface is considered to be less susceptible to tail stall
than a standard horizontal stabilizer. |
Stability |
The property of an air mass
to resist vertical displacement from its initial position.
If an air mass is stable, then an outside force is required
to raise it for cloud formation. On the other hand, unstable
air is buoyant and can rise to initiate cloud formation. |
Staging Bay |
A dedicated area behind and adjacent to each deicing bay, where aircraft await approval to enter the deicing bay. |
Standard
Terminal Arrival (STAR) Charts |
Designed to expedite air
traffic control arrival procedures and to facilitate transition
between en route and instrument approach operations. Each
STAR procedure is presented as a separate chart and may serve
a single airport or more than one airport in a given geographical
location. |
Static
Air Temperature (SAT) |
The ambient temperature
of air. Static Air Temperature (SAT) is measured with little
or no air motion past the temperature probe. This is the air
temperature that commonly appears in weather forecasts and
reports. SAT aloft is typically measured by balloon (See also
Outside Air Temperature and Total Air Temperature.). |
Stratiform
or Stratus Couds |
Clouds of extensive horizontal
development and a stable air mass. |
Sublimation |
A process where ice turns directly into water vapor without passing through a liquid state. |
Supercooled |
Water that remains in the
liquid state even though temperatures are below 0°C. Cloud
droplets can exist as a liquid at temperatures down to about
-40°C. |
Supercooled Large Droplets (SLD) |
Supercooled cloud droplets, freezing drizzle, or freezing rain with a Mean Volumetric Diameter greater than 50 microns. Due to their relatively large size and high mass, SLD are particularly hazardous to aircraft since they can impact the aircraft surfaces outside the ice protected regions. |
Supercooled Liquid Water (SLW) |
Liquid water at temperatures below 0°C. SLW is found in clouds, freezing drizzle, and freezing rain in the atmosphere. This water freezes on aircraft surfaces. Most aircraft icing occurs in supercooled clouds, which consist of SLW, sometimes with ice crystals. |
Supermental Weather Service Location |
An airport facility staffed with contract personnel who take weather observations and provide current local weather to pilots via telephone or radio. |
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Tactile Inspection |
An inspection requiring a person to physically contact specific aircraft surfaces. Tactile inspections, under certain circumstances, may be the only way of confirming that the critical surfaces of an aircraft are not contaminated. For some aircraft, tactile inspections are mandatory, as part of the deicing/anti-icing inspection process, to ensure that the critical surfaces are free of frozen contaminants. |
Taxiway |
A defined path on a land aerodrome established for the taxiing of aircraft and intended to provide a link between one part of the aerodrome and another. |
Temperature
Inversion |
Atmospheric condition where
temperature increases with altitude. |
Terminal Deicing Facility |
A deicing facility for one or several aircraft located at or near the terminal or other location where aircraft loading activity normally takes place. |
Terminal
Area |
A general term used to describe
airspace in which approach control service or airport traffic
control service is provided. |
Total
Air Temperature (TAT) |
Kinetic heating causes the
Total (or Ram) Air Temperature (TAT) to be warmer than the
Static Air Temperature (SAT). For example, if the SAT is -2C,
an aircraft traveling at 250 knots would observe a TAT of
approximately +5C. TAT is close to the temperature of the
wing leading edge, which also experiences ram rise (see also
Static Air Temperature and Outside Air Temperature). |
Tower |
A terminal facility that
uses air/ground communications, visual signaling, and other
devices to provide ATC services to aircraft operating in the
vicinity of an airport or on the movement area. Authorizes
aircraft to land or takeoff at the airport controlled by the
tower or to transit the Class D airspace area regardless of
flight plan or weather conditions (IFR or VFR). A tower may
also provide approach control services (radar or nonradar). |
Trace
Icing |
Ice becomes perceptible.
Rate of accumulation is slightly greater than the rate of
sublimation. Deicing/anti-icing equipment is not utilized
unless encountered for an extended period of time (over 1
hour). |
Trimmable
Stabilizer |
A horizontal stabilizer
that can be pitched to trim the elevator. This surface movement
can minimize the local angle of attack, so this form of tail
surface is considered to be less susceptible to tail stall
than a standard horizontal stabilizer. |
True
Airspeed |
The airspeed of an aircraft
relative to undisturbed air. Used primarily in flight planning
and en route portion of flight. When used in pilot/controller
communications, it is referred to as "true airspeed"
and not shortened to "airspeed." |
Turbojet
Aircraft |
An aircraft in which thrust
is produced entirely by the force of the air expelled by the
engine. The engine's main components are an inlet, a compressor,
a combustion chamber, a turbine, and a nozzle. The turbine
drives the compressor. |
Turboprop
Aircraft |
An aircraft in which thrust
is produced primarily by a propeller. The engine's main components
are an inlet, a compressor, a combustion chamber, a turbine,
and a nozzle. Typically there is a split turbine that drives
both the compressor and the propeller. |
Urgency |
A condition of being concerned
about safety and of requiring timely but not immediate assistance;
a potential distress condition. |
Vector |
A heading issued to an aircraft
to provide navigational guidance by radar. |
VFR
Terminal Area Charts |
(1:250,000) Depict Class
B airspace which provides for the control or segregation of
all the aircraft within Class B airspace. The chart depicts
topographic information and aeronautical information that
includes visual and radio aids to navigation, airports, controlled
airspace, restricted areas, obstructions, and related data. |
Visibility |
The ability, as determined
by atmospheric conditions and expressed in units of distance,
to see and identify prominent unlighted objects by day and
prominent lighted objects by night. Visibility is reported
as statute miles, hundreds of feet or meters. |
Visible
Moisture |
Moisture in the form of
clouds or precipitation. |
Visual
Flight Rules (VFR) |
FARs that govern flight
in visual meteorological conditions-flight by reference to
the natural horizon and surface. |
Visual
Flight Rules (VFR) Conditions |
Weather conditions equal
to or better than the minimum for flight under visual flight
rules. The term may be used as an ATC clearance/instruction
only when: an IFR aircraft requests a climb/descent in VFR
conditions, the clearance will result in noise abatement benefits
where part of the IFR departure route does not conform to
an FAA approved noise abatement route or altitude, or a pilot
has requested a practice instrument approach and is not on
an IFR flight plan. |
VOR |
A ground-based electronic
navigation aid transmitting very high frequency navigation
signals, 360 degrees in azimuth, oriented from magnetic north.
Used as the basis for navigation in the National Airspace
System. The VOR periodically identifies itself by Morse Code
and may have an additional voice identification feature. Voice
features may be used by ATC or FSS for transmitting instructions/information
to pilots. |
Water
Vapor |
The gas phase of water. |
Water Spray Endurance Test (WSET) |
A laboratory test that measures the endurance time of anti-icing fluids under conditions of light freezing precipitation. This test is used to classify and to certify fluids according to SAE AMS specifications. |
Wind
Shear |
Any rapid, horizontal, or
vertical change in wind direction or speed. |
World
Aeronautical Charts (WAC) |
(1:1,000,000) Provide a
standard series of aeronautical charts covering land areas
of the world at a size and scale convenient for navigation
by moderate speed aircraft. Topographic information includes
cities and towns, principal roads, railroads, distinctive
landmarks, drainage, and relief. Aeronautical information
includes visual and radio aids to navigation, airports, airways,
restricted areas, obstructions, and other pertinent data. |
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