Private Aviation Glossary

Glossary

PHRASEMEANING
0001: United States President is on board
1ST FREEDOMthe right to overfly a country without landing (for example: Singapore Airlines from the United States to Singapore, overflying Russia)
2ND FREEDOM:the right to stop in a country for refueling without transferring payload (for example: Airblue, a Pakistani airline, from the UK to Pakistan via Turkey for refueling)
3RD FREEDOM:the right to carry payload from one’s country to another (for example: Air Canada flying from Canada to China)
4TH FREEDOM:the right to carry payload from another country to one’s own (for example: Air Canada flying back from China to Canada)
5TH FREEDOM:the right to carry payload from one’s country to another, then on to a third one (for example: Jet Airways, an Indian airline, from India to Belgium then on to Canada)
6TH FREEDOM:the right to carry payload from one country to one’s own, then on to a third one (for example: Our Airline, formerly known as Air Nauru, from the Solomon Islands to Nauru then on to Kiribati)
7500:  Hijack
7600:  Loss of radio (NORDO). Pilot tunes 7700 for 1 minute, then 7600 for 15 seconds.
7700:  Emergency situation
7TH FREEDOM: the right to carry payload between two foreign countries as a stand-alone service (for example: OpenSkies, a British airline, from France to the United States)
8TH FREEDOM:the right to carry payload within a foreign country, as part of a flight originating/terminating in one’s own country (for example: Qantas from Australia to a US city, then on to a second US city)
9TH FREEDOM:the right to carry payload within a foreign country as a stand-alone service (for example: a hypothetical New Zealand airline flying between two cities in Australia)
AAIB: Air Accident Investigation Branch of the Department of Transportation of the United Kingdom. Its role is to investigate air accidents. The letters AAIB also refer to equivalent organizations in Iceland, Singapore and Switzerland, among others. In the United States, the NTSB plays that role.
AB: Air Base. More often used when describing a military airport.
ACARS: Aircraft Communication Adressing and Reporting System
ADELT: Automatically Deployable Emergency Locator Transmitter. See ELT.
ADF: Automatic Direction Finder. Radio compass giving a relative bearing to a NDB.
ADI: Attitude Deviation Indicator. Enhanced artificial horizon with pitch and roll information. It is part of a flight director system.
ADT: Approved Departure Time
AEROSPACE ENGINEERINGEncompasses the research, design, development, construction, testing, science and technology of aircraft and spacecraft. Divided into two overlapping branches: aeronautical engineering and astronautical engineering.
AFB: Air Force Base
AFCS: Automatic Flight Control System. It is an advanced autopilot.
AFDS: Autopilot and Flight Director System
AGL: Above Ground Level
AIR AMBULANCEAir charter of a private jet, helicopter or turbo-prop certified to provide air transport to medical patients.
AIR CHARTERAct of renting or leasing a jet or plane for transport of cargo or passengers.
AIR CHARTER AGENTOne who is contracted on behalf of the end user of the charter flight. A charter agent works to ensure fair market value, reasonable safety measures are followed and to provide flexibility and options for the purchaser of the air charter flight.
AIR TRAFFIC CONTROLLERThe service to pilots that promotes the safe, orderly and expeditious flow of air traffic. Usually each country operates its own Air Traffic Control service. In the UK, Air Traffic Control services are provided by NATS.
AIRCRAFTA machine used for flight which gains lift or support from the air.
AIRCRAFT INSURANCECovers the operation of aircraft and the risks involved in aviation.
AIRMET: Aircraft’s Meteorological Information. A type of weather advisory regarding certain weather conditions (turbulence, icing, low visiblity) which could pose a threat to only smaller types of aircraft. SIGMET is a more inclusive type of advisory.
AIRPORTAn area that is used for takeoffs and landings of aircrafts. Airports can be on land or water.
AIRSHOW:A cabin information system that displays the aircraft's position on a moving map, with altitude, time to destination, outside temperature and other flight data.
AIRSPEEDSpeed of an aircraft relative to its surrounding air mass.
AIRWAY DISTANCEActual distance flown by the aircraft between two points (as opposed to straight line). Calculated after deviations required by Air Traffic Control and navigation along published routes.
ALTERNATE AIRPORTAn airport other than the intended airport, where an aircraft can land for safety or other reasons.
ALTERNATE: Airport indicated on a flight plan where it is possible to divert the aircraft from its scheduled destination (in case of bad weather or any other major situation).
ALTIMETER SETTING: Barometric pressure reading in millibars (for example: 1015), or inches of mercury (for example: 29.80) used to set a pressure altimeter’s sub-scale to QFE or QNH.
ALTITUDEVertical distance between an object and mean sea level.
AOCAn Air Operator's Certificate is the approval granted from a national aviation authority to an aircraft operator to allow it to use aircraft for commercial purposes. This requires the operator to have personnel, assets and systems in place to ensure the safety of its employees and the general public. The certificate will list the aircraft types and registrations to be used, for what purpose and in what area - specific airports or geographic region.
AOC:Air Operator's Certificate. It specifies the type of operation that the operator is licensed to perform and sets out the conditions under which those authorised operations will be performed. Issued in the UK by the Civil Aviation Authority (CAA).
APP: Approach control
APPROACH (departure) CONTROLThis is radar-based air traffic control, associated with the tower at larger airports. Separates aircraft traffic from outside the immediate airport area to a distance of about 40 miles.
APRONHard-surfaced or paved area around a hangar. See also Ramp.
APU:Auxiliary Power Unit. An onboard source of power that enables air conditioning, heating, galley facilities and cabin lighting to be used on the ground when the main engines are not operating. The APU is actually a small additional jet engine that doesn't provide any forward thrust and acts solely as a generator of electricity.
ARTCC: Air Route Traffic Control Centre
ASI: Airspeed Indicator
ATA: Actual Time of Arrival
ATC: Air Traffic Control
ATCC: Air Traffic Control Centre
ATIS: Automatic Terminal Information Service. Automatically recorded message transmitted on a particular frequency, containing current weather conditions, QNHsetting, active runways, etc., provided at the major airports.
AUGMENTED CREW:See Heavy Crew
AVGAS: Aviation Gasoline. Usually followed by the octane rating. Used by piston-engined aircraft.
AVIATIONThe operation, development, production and use of aircraft.
AVIONICSThe electronic control systems airplanes use for flight such as communications, autopilots, and navigation.
AVTUR: Aviation Turbine fuel (kerosene). Used by turboprops and jet aircraft.
BASE: Base of operations or a HUB for an airline. The base leg is also one of the many words describing the approach segments. See Final for a diagram.
BEECHCRAFT HAWKERBusiness jet aircraft built by Hawker Beechcraft Corporation (HBC) between 2006 and 2013.
BLACK BOX: Popular name given to either the CVR or the FDR used to investigate an accident.
BLEED AIR: Hot compressed air taken from turbine engines.
BLOCK FLYING TIMETime between an aircraft first moving from its parking place for the purpose of taking off until it comes to rest on the designated parking position and until all engines are stopped.
BLOCK HOURS:The advance purchase of a specific number of hours of flying time, to be flown as and when required.
BLOCK RATESRate for scheduling significant amounts of air charter time in advance under a prearranged agreement.
BLOCK SPEEDThe average speed at which an aircraft covers a specific distance. Based on “block-to block,” or “door-to-door “ (gate-to-gate).
BOEING BUSINESS JETA series of Boeing airliners designed for the corporate jet market and seating between 25 and 50 passengers within a luxurious configuration.
BOMBARDIERA family of business jets.
BOMBARDIER GLOBAL EXPRESSA large cabin, ultra long range business jet manufactured by Bombardier Aerospace in Toronto, Ontario, Canada.
BRGBearing. Horizontal direction to/from a point, expressed in degrees (for example: 000 or 360 is North, 090 is East).
BUSINESS JETA smaller Commercial jet aircraft model, configured to transport smaller groups of people.
BUSINESS JET CHARTERAn aircraft that is chartered for the purpose or use in business transportation.
CAA: Civil Aviation Authority. An organization in charge of defining aviation safety standards. The United Kingdom and New Zealand, among others, have organizations with that exact name and role. In the United States, CAA stood for the Civil Aeronautics Administration, a fore-runner of today’s FAA.
CAB: Civil Aeronautics Board. Former government agency of the United States responsible, among other things, of investigating air accidents (duties taken over by the NTSB) and controlling which routes the airlines could fly and what fares they could charge (prior to the Airline Deregulation Act).
CALLSIGN: Phrase used in radio transmissions to identify an aircraft, before proceeding to actual instructions. A callsign for a commercial aircraft may be “Swissair 111” or “TWA 800”. As for a private plane, it could be something like “Cessna 13 Whisky”, “Baron 232 Zulu” or “November 17 Victor”. Military callsigns, including transport of heads of state or government officials are more diverse and depend on squadron, type of mission, etc.
CAPT: Captain
CARBON CREDITKey component of national and international emissions trading schemes. They provide a way to reduce greenhouse effect emissions on an industrial scale by capping total annual emissions and letting the market assign a monetary value to any shortfall through trading. Credits can be exchanged between businesses or bought and sold in international markets at the prevailing market price. Credits can be used to finance carbon reduction schemes between trading partners and around the world.
CARBON EMISSIONSThe principal greenhouse gas emission. Carbon is largely thought to be the most dangerous greenhouse gas.
CARBON OFFSETMonetary contributions to renewable energy research and production projects, designed to reflect and mitigate the user's own greenhouse gas emissions eg through air travel.
CARDINAL ALTITUDEAn altitude, or flight level, of a thousand feet.
CAS: Calibrated Airspeed. IAS corrected for air density and compressibility.
CATERINGA service provided for luxury jet charters. Catering is the provision of in-flight meals.
CDI: Course Deviation Indicator. The vertical needle of a VOR indicator which shows the aircraft’s position relative to the selected RADIAL.
CEILING: Height above ground or water level of the base of the lowest layer of cloud, below 20,000 feet, covering more than half of the sky. Service ceiling also means an aircraft’s DENSITY ALTITUDE at which its maximum rate of climb is lower or equal to 100 feet per minute. The absolute celing is the highest altitude at which the aircraft can maintain level flight.
CERTIFICATE See AOCCERTIFICATE See AOC
CESSNAAn American general aviation aircraft manufacturing corporation headquartered in Wichita, Kan. Known for small, piston-powered aircraft, as well as business jets.
CFB: Canadian Forces Base.
CHARTER BROKER:An individual or company that acts as a middle man between the charter operators and the charter passengers. A good broker will be able to find the best deal for his customer's needs.
CHARTER CARDPre-paid air charter plan, either for a block of charter hours at a pre-defined fee, or a set debit balance in dollars.
CLEARANCE: Authorization given by ATC to proceed as requested or instructed (for example: “Cleared for take-off”, “Cleared for visual approach”, “Cleared to land”)
CLUB SEATING:A seating layout where pairs of seats face each other, as in a railway carriage compartment, rather than all face the same way, as on a bus. The club configuration is more sociable and enables easy conversation between occupants.
COAST TRACK: Status of an aircraft that is no longer giving a radar return. The air traffic control screen will display this status (usually with the acronym “CST”) and will temporarily continue displaying the aircraft’s movement at the last heading and speed, as if it was “coasting”.
COMAT: Company Material. NON-REVENUE cargo, such as aircraft spare parts.
COMMERCIAL FLIGHTA "commercial" flight is when the customer has paid for a commercial charter of that aircraft. The rules for commercial flights are more stringent than private flights and include limitations on crew duty hours, runway length and other safety considerations. For commercial private jet charter the minimum stopping distance for the aircraft is multiplied by 1.6, to create the minimum landing distance required (LDR).
COMMUTER OPERATORA regional, scheduled airline. In this book limited to that operator with adequate fleet capacity as to be available of charter. Not all commuter airlines charter, because of the limitations of aircraft and crew availability.
CONNECTION: Transfer between two different flights at an intermediate airport (for example: flight 123 from New York to Miami followed by flight 456 from Miami to Sao Paulo). If a passenger’s flights are operated by two different airlines, they may check baggage or obtain boarding passes for the entire itinerary directly at the departure city’s airport, pursuant to interlining agreements or airline alliances. A connection is not the same as a stopover.
CONTRAILSStreaks of condensed water vapour created in the air by aircraft flying at high altitudes; aka vapour trails.
CONTROLLED AIRSPACEDefined airspace where Air Traffic Control service is provided to IFR flights and to VFR flights.
CORPORATE OPERATORA company flight department which has earned a "Part 135" certificate to carry passengers for compensation.
CROSSWINDWinds blowing perpendicular or not parallel to the runway or the aircrafts flight path.
CROSSWIND: Wind perpendicular to the motion of the aircraft. The crosswind leg is also one of the many words describing the approach segments. See Final for a diagram.
CRT: Cathode Ray Tube. Television-like screens used in flight decks of new-generation aircraft, replacing the conventional instruments. See also EFIS.
CRUISE SPEEDThe normal speed attained at altitude once the aircraft is no longer climbing and is en route.
CRUISING ALTITUDEA level altitude maintained by an aircraft while in flight.
CST: See Coast track. CST may also stand for Central Standard Time.
CVR: Cockpit Voice Recorder. One of the so-called “black boxes”. It is a device recording the last 30 minutes of sound inside the cockpit, before impact. Sounds recorded include all conversations, radio transmissions, and background noise.
CWR: Color Weather Radar
DASSAULT FALCONA family of business jets manufactured by Dassault Aviation.
DCT: Direct
DEAD HEADA leg of an air charter with no cargo or no passengers. Commonly the return leg, but may also be the repositioning.
DEAD LEG:See empty leg.
DEAD-HEADING: See Repositioning.
DECISION HEIGHTIn an instrument approach flight, the height at which a decision must be made to either continue the approach or to execute a missed approach.
DEMURRAGErefers to the charges that are levied by an operator when a charterer keeps an aircraft after the completion of the flight. For example, if an aircraft is chartered for two flights with a week intervening, an aircraft may remain or lay over at the destination. The charterer will pay demurrage charges for every day that this aircraft remains at the charterer's destination without returning home.
DENSITY ALTITUDE: pressure altitude (as indicated by the altimeter) corrected for air temperature.
DEPRECIATIONMethod to account for assets whose value decrease over time because of factors such as age, wear or market conditions.
DH: Decision Height. Height on a precision approach at which the pilot must have the runway approach lights in sight to continue descent, or if not, initiate a GO-AROUND. Below the DH, the pilot has no other choice than land the plane.
DI: Direction Indicator. A gyro instrument which indicates the magnetic heading of an aircraft. The DI, also known as the directional gyro (DG), is free of the turning errors associated with magnetic compasses but is prone to precession (wander) and must be reset against the magnetic compass at intervals.
DIRECT FLIGHT: A flight that operates from point A to point B without a connection. A direct flight is not necessarily non-stop.
DME: Distance-Measuring Equipment. A combination of ground and airborne equipment which gives a continuous slant range distance-from-station readout by measuring time-lapse of a signal transmitted by the aircraft to the station and responded back. DMEs can also provide groundspeed and time-to-station readouts by differentiation.
DOUBLE ROUND TRIPOccurs when an air charter itinerary is designed such that it is more costly to keep the plane away from base than it would be to return home empty the report for pick up to complete the air charter itinerary.
DOWNWIND: One of the many words describing the approach segments. See Finalfor a diagram.
DUTY TIMEA pilot or crew member is logging duty time whenever he is serving in any capacity. There are safety restrictions on duty time to ensure pilots and crew are sufficiently rested.
DVOR: Doppler VOR.
EAT:  Estimated (or expected) Approach Time
ECAM:  Electronic Centralized Aircraft Monitor. A form of CRT
EFIS(Electronic Flight Information Systems) Glass cockpit avionics that integrate all flight parameters into one optimized instrument. These modern systems offer enhanced reliability, reduced weight, simplified installation and overall cost savings.
EGPWS(Enhanced Ground Proximity Warning System) Uses aircraft inputs such as position, attitude, air speed and glide slope, which along with internal terrain, obstacles, and airport databases predict a potential conflict between the aircraft's flight path and terrain or an obstacle.
EGPWS(Enhanced Ground Proximity Warning System) Based on aircraft inputs such as position, attitude, air speed and glide slope, as well as internal terrain, obstacles, and airport databases. Used to predict a potential conflict between the flight path and terrain or an obstacle.
EGT:  Exhaust Gas Temperature. One of the flight deck’s engine gauges.
EICAS:  Engine Indication and Crew Alerting System. A CRT display indicating engine performance and alerts.
ELB:  Emergency Locator Beacon. See ELT (below).
ELT(Emergency Locator Transmitter) A radio transmitter activated automatically by the impact of an accident. Emits a warbling tone on the international emergency frequencies of 121.5 MHz, 243 MHz and (newer models) 406 MHz. ELT signals can be received by nearby FAA facilities, aircraft overhead, and search and rescue (SARSAT) satellites.
EMPTY LEGSA re-positioning flight where the aircraft is flying empty. Chartering an empty leg can cost significantly less than a full-price charter.
ER:  Extended Range. Suffix used by some aircraft models (for example: Boeing 767-300ER)
ETA:  Estimated Time of Arrival
ETD:  Estimated Time of Departure
ETE:  Estimated Time Enroute
ETOPS:  Extended-range Twin Operations. Certification given to two-engine aircraft for long overwater flights. Popular deformation of this term is “Engines Turning Or Passengers Swimming”!
EXECUTIVE JET CHARTERAn aircraft that is chartered for the purpose or use in the transportation of executives. Typically the aircrafts that are chartered are midsize jets.
F/A:  Flight Attendant. Also known as Air Hostess in the UK, formerly known as Steward(ess) in North America.
F/E:  Flight Engineer. Also known as Second Officer.
F/O:  First Officer. Also known as Co-Pilot.
FAA(Federal Aviation Administration) The US Department of Transportation’s agency for aviation in the United States, which regulates airports, aircraft manufacturing and parts certification, aircraft operation and pilot certification. Also operates Air Traffic Control, purchases and maintains navigation equipment, certifies airports and aids airport development.
FBOFixed Base Operator - provides ground services for air charter clients such as: onsite mechanic, fuel service, catering, ground transportation and other services.
FBW:  Fly-By-Wire. Aircraft controls where the pilot’s commands (bank, yaw…) are transmitted to control surfaces electronically or via fiber optics, instead of mechanical linkage. Also called FBL (Fly-By-Light).
FDR:  Flight Data Recorder. One of the so-called “black boxes”. It is actually painted bright orange to be easily identified among aircraft debris, and records various parameters such as altitude, heading, airspeed, engine statistics, etc… It is used to investigate in the case of an accident.
FEATURED CHARTERFEATURED CHARTER The chartering of a specific aircraft to a specific destination. Featured charters often include hotel accommodations, luxury car rentals, golf and spa packages etc.
FERRY FLIGHTA flight for the purpose of returning an aircraft to base, delivering an aircraft from one location to another, moving an aircraft to and from a maintenance base.
FIDS:  Flight Information Display System. Real-time flight arrival and departure data for an airport, either as a board inside or near the airport terminal or a virtual version on a website or teletext.
FIN NUMBER:  See FN below.
FINAL:  Final Approach. One of the many words describing the approach segments. The part of a landing sequence or aerodrome circuit procedure in which the aircraft has made its final turn and is inbound to the active runway. See picture on the right.
FL:  Flight Level. Altitude at barometric setting of 1013.2 millibars or 29.92 inches of mercury, expressed in rounds hundreds of feet. This is usual mostly above 18,000 feet. FL350 is 35,000 feet.
FLEET MANAGERA commercial aviation entity developed to subcontract the maintenance and operation of corporate aircraft, which are often chartered out to the general public.
FLIGHT ATTENDANT:A member of the crew dedicated to attending to the passengers during the flight. Often able to meet advance requests for specific catering, drinks, magazines, flowers or other requirements.
FLIGHT PLANFiled with an Air Traffic Control Facility a flight plan is the specific information regarding the flight or intended flight of an aircraft.
FLIGHT TIME:The time between take-off and landing. Excludes any time spent taxiing to and from the stand.
FMS(Flight Management System) A regional office of the United States Federal Aviation Administration that concentrates on enforcing regulations.
FMS(Flight Management System) A regional office of the FAA that enforces regulations.
FMS:  Flight Management System
FN:  Fleet Number. Internal number, for the use of the airline, identifying a particular aircraft within the fleet.
FOD(Foreign Object Debris) refers to anything on the runway that may cause hazards to aircrafts or people on the ground.
FOD(Foreign object debris) Anything on the runway that may cause hazards to aircraft or people on the ground.
FPL:  Filed Flight Plan
FPM:  Feet Per Minute. Unit of measure of an aircraft’s rate of climb or descent.
FRACTIONAL OWNERSHIPThe purchase of a "share" of an aircraft. Fractional owners are guaranteed access to an aircraft but not necessarily the same one each time. They usually pay a fixed monthly maintenance fee as well as an hourly fee.
FREEDOM OF THE AIR:  Commercial aviation right governing carriage of PAYLOADbetween or within countries. The following are recognized by the ICAO:
FUEL SURCHARGEA charge for the increased price of fuel to cover fuel price increases.
FUSELAGEAn aircraft's main body structure housing the flight crew, passengers, and cargo.
GAT:Abbreviation for  General Aviation  Terminal. The  Handling Agents  will often be located here as GA terminals are much quieter than scheduled terminals.
GENERAL AVIATION:The aviation industry categorises flights as either Scheduled, Cargo, Military or General. Non-airline passenger flights fall in the broad General Aviation category, however the terms Business Aviation or Executive Aviation are frequently used to differentiate private jet charter flights from light aircraft enthusiast flights.
GNDGround
GO-AROUND:  Balked approach, when the aircraft climbs away from the runway during the approach, to either start the approach again, or proceed to the ALTERNATE AIRPORT.
GPS:  Global Positioning System (Navstar). Navigational system using orbiting satellites to determine the aircraft’s position on the Earth. Developed at first for military use, then widespread on commercial and private aircraft, it is now expected to replace the ground-based navigational systems for its accuracy and reliability.
GPU:  Ground Power Unit
GPWS:  Ground Proximity Warning System. A radar-based flight deck system to give pilots audible warning by means of horns, hooters, taped or synthetic voices of terrain close beneath an aircraft’s flight path. One of the GPWS’ warnings might be: “TERRAIN! WHOOP WHOOP! PULL UP!” or “WINDSHEAR! WINDSHEAR!”.
GREAT CIRCLE DISTANCEThe shortest distance between two points on a globe. All distances shown in distance tables in the Air Charter Guide are "great circle distance".
GROUND SPEEDThe speed of an aircraft relative to the surface of the earth.
GROUND TRANSPORTATIONA service provided for luxury jet charters before or after the flight. Ground transportation can be limo service or luxury car rental.
GS:  Glideslope. Vertical guidance, part of an ILS, establishing the safe glidepath to a runway. A standard ILS glideslope is 3 degrees.
GULFSTREAMBusiness jet aircraft designed and manufactured by Gulfstream Aerospace Corporation, a wholly owned subsidiary of General Dynamics. Gulfstream’s fleet consists of these models: G150, G280, G350, G450, G500, G550, and G650.
HANDLING AGENT:A company appointed by the operator to greet and ease their passengers' passage through an airport. Will typically feature a dedicated car park, VIP lounge, security and immigration liaison and baggage porterage.
HANGARAn enclosed structure for housing aircraft. Originated with lake-based floating homes of the original German Zeppelins in which they were "hung" from cables.
HDG:  Heading. The direction in which an aircraft’s nose points in flight in the horizontal plane, expressed in compass degrees (for example: 000 or 360 is North, 090 is East).
HEAVY CREW:Flying with one or more additional flight crew members. On occasion an ultra-long range aircraft might carry additional pilots to allow each to rest in rotation and counter the onset of fatigue.
HEAVY JETAn aircraft with a minimum takeoff weight of 255,000 lbs.
HEAVY:  Suffix used in radio transmission callsigns (for example: “United 492 Heavy”) to indicate the aircraft is capable of generating WAKE TURBULENCE.
HELICOPTERA rotor driven aircraft that uses vertical axes with pitched blades to generate lift and stability.
HELIPADUsed by helicopters for takeoffs, landings and occasionally for parking.
HELIPORTThe area of land or water used for the landings and takeoffs of helicopters, the buildings, structures and grounds.
HOLDING PATTERN:  Manoeuver consisting of making the aircraft turn around the aerodrome at an assigned altitude, while awaiting further ATC instructions.
HORSE POWERThe motive energy required to raise 550 lbs. one foot in one second, friction disregarded.
HSI:  Horizontal Situation Indicator. A cockpit navigation display, usually part of a flight-director system, which combines navigation and heading.
HUB-AND-SPOKE:  Route system in which an airline will fly the majority of its flights from/to the same city (the hub), thus offering several connecting possibilities, as opposed to fly a series of point-to-point flights. Example: instead of flying non-stop from Los Angeles to New York, from Phoenix to Washington, from Las Vegas to Boston, etc., an airline will offer all these routes via its hub in Chicago.
I/C:  In Charge.
IAS:  Indicated Airspeed. Airspeed indicated by the Airspeed Indicator, without correction for position error, altitude, or outside air temperature.
IATACode International aviation codes used by international airports
ICAO(International Civil Aviation Organization) An agency of the United Nations, charged with developing principles and techniques of international air navigation.
IDENT:  SQUAWK function of a transponder. When the “Ident” button is activated, an aircraft will briefly appear more distinctly on a radar scope. Used for identification or acknowledgement purposes.
IFR(Instrument Flight Rules) Applies to flights permitted to penetrate clouds and low visibility conditions using cockpit flight instruments and radio navigation. Aircraft must be equipped with proper instruments and pilots must be qualified and hold current IFR ratings. Flight plans and ATC clearances are required, and IFR flights are monitored and kept eparated by Air Traffic Control, usually by radar.
ILS(Instrument Landing System) A precision instrument approach system used to direct landings during periods of low ceilings or poor visibility. Using radio transmitters at the runway ends, the ILS provides precise left-right and up-down indications to the pilot.
INDICATED AIR SPEEDThe speed displayed by the aircraft’s air speed indicator device.
INS:  Inertial Navigation System. It uses gyroscopes and other electronic tracking systems to detect acceleration and deceleration, and computes an aircraft’s position in latitude and longitude. Its accuracy, however, declines on long flights. Also called IRS, or Inertial Reference System.
INSTRUMENT APPROACH:An airport installation that enables the aircraft to safely land in poor visibility. All commercial airports and all but the smallest general aviation aerodromes have at least one instrument approach. A private jet charter can be arranged to any licensed airport or aerodrome with a runway sufficient for the aircraft.
INSTRUMENT METEROLOGICAL CONDITIONSConditions such as visibility, distance between clouds, ceiling level that does not meet the standard for visual meteorological conditions.
INTERNATIONAL AIRPORTAn airport designated to carry out the duties of customs and immigrations along with other duties.
JET AIRLINERAn airliner that uses jet engine propulsion. Capable of efficiently functioning at a high altitudes and high speeds.
JET CARDS:Schemes by which operators sell individuals block hours on their aircraft.
JET CHARTERAct of hiring crew; leasing an aircraft for the purpose of private air transportation.
JET CHARTER BROKERAn intermediary who facilitates the leasing or purchasing of air charter. See also Private Jet Broker.
JET ENGINEAn internal combustion air-breathing duct engine
JET STREAMHigh altitude, High Speed winds that in the United States blow from west to east.
JOINT OWNERSHIPPurchase or lease of a complete aircraft by a relatively small number of owners, often through a partnership or limited liability corporation.
KNOT(nautical mile per hour) Common measure of aircraft speed, equaling 6,080 feet or about 1.15 miles.
KNOT (KT):  Standard unit of speed in aviation and marine transportation, equivalent to one nautical mile per hour. One knot equals 1.1515 mph, and one nautical mile equals 6,080 feet. The word “knot” replaces “nautical miles per hour”, and one should never say for example “60 knots per hour”.
LAT: Latitude
LAYOVERA rest stop away from home base for the aircraft and crew in the middle of a flight.
LEARJETA private luxury business jet aircraft originally manufactured by Learjet in Wichita, Kan. Now owned by Bombardier. The word is also used generically to refer to small business jets.
LEGA single direction of travel between two points. For an air charter itinerary a leg could be represented by repositioning and fuel stops.
LIFTChartering an aircraft for cargo or passenger transport.
LN:  Line Number. Priority of the aircraft in the MANUFACTURER‘s line. A Boeing 757-200 with a LN of 275 was the 275th plane of its type to be built.
LOC:  Localizer. The azimuth guidance portion of an instrument landing system.
LON(G):  Longitude
LORAN:  Long-Range low-frequency Radio Navigation. Its range is about 1,200 nm by day, and 2,300 nm by night.
LROPS:  Long Range Operational Performance Standards. Certification intended to replace ETOPS as it would include all types of aircraft (not just twin-engine).
LUXURY JET CHARTERChartering a luxuriously appointed aircraft for business or pleasure.These jets provide five-star catering, ground transportation, and lavish accommodations in excess of needs.
MACH NUMBER:  Ratio of true airspeed to the speed of sound. Mach 1 is the speed of sound at sea level. Its value is approximately 760 mph.
MAG:  Magnetic
MAGNETIC COURSE:  Intended horizontal direction, measured in degrees clockwise from the magnetic north.
MANUFACTURER:  Aircraft builder, such as Airbus, Boeing, Embraer, etc.
MATCH SPEEDThe ratio of true airspeed to the speed of sound
MAYDAY:  The ultimate international radio distress call, indicating imminent danger to the life of the occupants onboard and requiring immediate assistance. Its slightly less prioritary equivalent is Pan Pan. The anecdote says it comes from a French pilot who said over the radio “Venez m’aider” (“help me”) to an English-speaking controller, who only understood “Mayday”.
MEDEVACMEDical EVACuation - the term commonly applied to an aircraft used to transport injured patients to hospital. See also Air Ambulance.
METAR:  Aviation routine weather report. Format for shorthand weather information reporting using a standardized set of codes and abbreviations (for example: BKN broken clouds, OVC overcast, CAVOK ceiling and visibility okay, etc.) Acronym possibly comes from the French “Météorologie Aviation Régulière” (routine aviation weather).
MID-SIZE JETSAircraft designed for longer-range travel such as transcontinental flights. Provide larger passenger capacity.
MLS: Microwave Landing System. A microwave-based instrument approach system intended to replace ILS in the 1990s and claimed to offer a number of advantages such as the ability to fly segmented and curved precision approaches.
MSL:  Mean Sea Level
MSN:  Manufacturer Serial Number. Internal number, for the use of the MANUFACTURER, identifying a particular aircraft within the same model.
MTOW:Maximum Take-Off Weight
NARANational Aircraft Resale Association
NATIONAL AIRSPACE SYSTEMThe network of airspace, navigational services facilities and equipment.
NATSProvider of Air Traffic Control services to aircraft flying in UK airspace and over the eastern part of the North Atlantic.
NAUTICAL MILEUsed to measure distances at sea. 2,025 yards or 6,076 feet.
NAVAIDSNavigational aid is any form of device that guides a pilot and his aircraft from one area to another. There are many different kinds of Navaids in use to provide guidance, location, and direction, the most popular being the Global Positioning System (GPS) but the term can also apply to a map, a beacon or a compass.
NAVAIDSAny type of device that guides an aircraft from one area to another. Examples include the Global Positioning System (GPS), a map, a beacon or a compass.
NAVIGATIONRecording, planning and controlling the movement of an aircraft from one point to another.
NBAANational Business Aviation Association.
NDB:  Non-Directional Beacon. A medium-frequency navigational aid which transmits non-directional signals, superimposed with a Morse code identifier and received by an aircraft’s ADF.
NM:  Nautical Miles.
NON-REVENUE:  Passenger flying free of charge, on a STANDBY basis, by presenting an airline/aviation employee pass. Non-Revenue passengers may or may not be on duty, therefore this expression also applies to repositioning crew members. Also known as Non-Rev for short.
NON-STOP:  A direct flight that operates from point A to point B without a stopover.
NON-TOWERED AIRPORTAn airport without a control tower
NORDO:  No radio. Aircraft without a radio or experiencing a radio failure.
NO-SHOW: Passenger with a confirmed reservation, who failed to check-in or board on time.
NOTAM:  Notices To Airmen. Issued by the country’s aviation authority to inform pilots of new or changed aeronautical facilities, services, procedures, or hazards, temporary or permanent.
NTSB:  National Transportation Safety Board. A United States government organisation in charge of investigating in the case of an accident. In many countries, an AAIB fulfills that role.
OAT:  Outside Air Temperature
ONE-WAYSThe air charter of an aircraft for a particular leg of an existing air charter itinerary.
OPERATORResponsible for the licensing, maintenance, safety and operations of one or more private charter aircraft. The operator is not always the owner of the luxury jet, business jet or private jet that is available for charter.
PAN PAN:  International radio urgency call. It usually indicates a threat to the safety of an aircraft or its passengers. It is, however, less urgent than Mayday. Pan Pan comes from the French word “Panne” which means “failure”.
PATTERNThe path of aircraft traffic around an airfield, at an established height and direction. At tower-controlled fields, Air Traffic Controllers supervise the pattern by radio (or in non-radio or emergency conditions by red and green light signals.
PAX: Passengers
PAYLOAD:  Revenue passengers and/or cargo, or more specifically their combined weight.
PHONETIC ALPHABET: Spelling technique under which each letter is replaced by a word starting with the letter in question (for example: “Alfa, Bravo, Charlie” to spell “ABC”). The current alphabet is also known as the ICAO spelling alphabet, the international radiotelephony spelling alphabet or the NATO phonetic alphabet.
PILOT IN COMMANDThe pilot responsible for safety and operations of the aircraft during flight.
PIREP:  Pilot report. Weather observations reported by a pilot in flight.
PNR:  Passenger Name Record. Another word for Reservation.
POB:  Number of Persons On Board. Also SOB, Souls On Board.
POH:  Pilot’s Operating Handbook. It is the aircraft’s “owner’s manual”.
POINT TO POINT PRICINGUsually occurs when one charters a jet from a location other than where that aircraft is based; also known as a transient aircraft charter. Point to point pricing is typically the result of an empty leg being chartered for a portion of the primary routing of the original air charter itinerary.
POSITIONINGWhen aircraft is ferried from its originating airport to another airport for departure.
POSITIONING FLIGHT:To fly an aircraft empty to a particular airport in order for it to be able to commence a flight from that airport.
PRECIPITATIONWater particles that fall from the atmosphere and reach the surface of the earth.
PREFFERED VENDORSThe vendor of choice for supplemental lift. Air charter agents, jet charter brokers and charter jet operators compile a list of air charter vendors for each region that they service.
PRIVATE AIRPORTAn airport used by general aviation and private aviation but is ineligible for use by scheduled airline travel.
PRIVATE FLIGHTA "private" flight is when an owner of the aircraft (or one of their friends or family) are using the aircraft for private use. No money changes hands for the use of the aircraft. (As opposed to a COMMERCIAL FLIGHT)
PRIVATE FLIGHTAn aircraft used by the owner, or one of their friends or family, for private use. No money changes hands, as versus a commercial flight.
PRIVATE JETAn aircraft that is privately owned.
PRIVATE JET BROKERAn intermediary who compares options from operators to facilitate selling or buying a private aircraft.
PRIVATE JET CHARTERHiring a private jet aircraft for a specific itinerary - as opposed to ownership or fractional ownership of an aircraft.
PROHIBITED AREAAn airspace area where flight is prohibited except by prior arrangement with the controlling agency.
PSI:  Pounds per Square Inch. Unit of measure for pressure.
QDR:  magnetic bearing from the station.
QFE:  atmospheric pressure at aerodrome elevation. With its sub-scale set to the aerodrome QFE an altimeter will indicate height above that airfield.
QFU:  magnetic orientation of runway in use.
QNE:  reading in feet on an altimeter set to 1013.2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
QNH:  altitude above mean sea level based on local station pressure.
QTE: true line of position from a direction-finding station.
QUJ:  true bearing
RADARTransmission of a radio pulse that provides information on range and elevation of objects in the path of transmitted pulses.
RADIAL: line from a VOR or NDB. For example, the 180 radial from a VOR represents a line south of that VOR.
RADIOWireless transmission device, based on electromagnetic signals, used by aircraft for communication.
RAMPThe hard-surfaced space in front of an FBO or terminal facility, used for deplaning, parking of aircraft, etc.
RAS:  Rectified Airspeed. IAS corrected for instrument position error.
RDO:  Radio
RELEASE TIMEA departure time restriction issued to a pilot by ATC (either directly or through an authorized relay) when necessary to separate a departing aircraft from other traffic.
REPOSITION:To undertake a positioning flight.
REPOSITIONING TIMEThe travel time for charter aircraft traveling to or from base en- route to the departure or from the destination of the particular air charter trip.
REPOSITIONING:  Flying from the point of destination to the next point of origin, without carrying any PAYLOAD (in the case of an aircraft) or without being responsible for payload (in the case of a crew member). Example: a scheduled U.S. airline operates a charter flight from Los Angeles to Lisbon. Then, payload-free, it flies to Paris, where it will board passengers and cargo for a scheduled flight back to Los Angeles. Also known as deadheading, ferry flight.
RESTRICTED AREA“Active” or “Hot” airspace that usually excludes civilian aircraft. May include airspace used for rocket flights, practice air-to-air combat or ground-based artillery practice. Temporary restricted areas are established for forest fires, natural disasters or major news stories. Flight through a restricted area may be authorized by the FAA.
REVENUE FLIGHT:Any flight that generates revenue for the operator. i.e. not a positioning, crew training or maintenance flight.
RMI:  Radio Magnetic Indicator. A navigation aid which combines DI, VOR and/or ADF display and will indicate bearings to stations, together with aircraft heading.
RNAV:  Area Navigation. A system of radio navigation which permits direct point-to-point off-airways navigation by means of an on-board computer creating phantom VOR/DME transmitters termed WAYPOINTS.
ROGER:  Commonly used word in aviation communications, to indicate that an instruction has been received and understood. Also, to roger is to read back and acknowledge an instrction. The origin of this word is the former RAF phonetic alphabet in which the letter R (for “received”) was for Roger, as opposed to Romeo today.
RON: Remain Overnight. Aircraft remaining overnight at the airport, either at the gate, remote parking stand or hangar. Airlines take advantage of RONs to perform maintenance, cleaning, etc. on the aircraft.
RPM: Revolutions Per Minute.
RUDDERAircraft control surface attached to the rear of the vertical stabilizer (fin) of the aircraft tail. Forces the tail left or right, correspondingly "yawing" the aircraft right or left. Rudder movement "coordinates" with the banking of wings to balance a turn. Controlled by left and right rudder (foot) pedals.
RUNWAYHard surface, smooth area used for aircraft landings and takeoffs.
RVR: Runway Visual Range. A horizontal measurement of visibility along a runway.
SCHEDULED AIR TRANSPORTATIONAirline Transportation regulation for scehduled air service requiring the FAA Part 121 certificate.
SCT: See SOCAL (below).
SECTOR:  Segment involving a take-off and landing (for example: a London-Bangkok-Sydney flight contains two sectors)
SEE AND AVOIDThe FAA requires all pilots to be responsible for keeping their aircraft separated from other aircraft when visual conditions permit spotting traffic. This also applies to IFR flights when pilots are operating in visual weather conditions, and to VFR flights being issued radar advisories.

SIGMET An advisory significant to the safety of ALL aircraft, usually issued in times of severe weather.
SELCAL: Selective Calling. A high-frequency system enabling air traffic control to alert a particular aircraft, by means of flashing light or aural signal in the cockpit, for receipt of a message without the crew having to maintain a listening watch. Used on long-haul over-ocean airline routes and by intercontinental business jets.
SHANWICK: ATC located in Shannon (Ireland) and Prestwick (Scotland, UK), hence the name. Shanwick looks after traffic in the Northern Atlantic coast of Europe.
SID:  Standard Instrument Departure. A standard IFR departure route enabling air traffic controllers to issue abbreviated clearances and thus speed the flow of traffic.
SIGMET:  Significant Meteorological Information. A type of weather advisory regarding severe weather conditions (thunderstorms, turbulence, icing, volcanic ash, etc.) which could pose a threat to all types of aircraft. AIRMET is a less inclusive type of advisory.
SMALL CABIN JETS:Private jets built primarily for efficiency and lower cost of operation. A good choice for business travel and still afford plenty of luxury on shorter journeys. Browse small cabin jets.
SOB: Souls (persons) On Board. Also POB, Persons on Board.
SPEED OF SOUNDEqual to 761 mph at sea level. Also known as Mach 1.
SPORT JET CHARTERAn aircraft chartered to transport members of sports teams to sporting events.
SQUAWK (TO): To transmit an assigned code via a transponder (for example: Delta 207 Heavy, Squawk 2044). The squawk is also the assigned code. Below are some standard special squawks:
SSR: Secondary Surveillance Radar. A radar system comprising a ground-based transmitter/receiver which interrogates a compatible unit in the aircraft (the transponder), providing instant radar identification without having to manoeuvre. Assigned four-digit transponder codes are referred to as squawk (see above) codes.
STAGE LENGTHThe distance of the air charter client's itinerary.
STAND:The part of the tarmac on which the aeroplanes stand when idle, separate from the taxiways and runways. Many airports allow private charter customers' cars to be escorted to and from the stand for transferring passengers and luggage. If preferred, or where airport regulations prohibit passenger vehicles airside, the handling agent will transfer passengers and luggage in their own vehicles.
STANDBY: In radio communications, is a word to ask the other person to wait for further instructions. A standby reservation is conditional and is on a waiting list, in case of any NO-SHOWS.
STAND-UP CABIN:A cabin designed for sufficient height to allow passengers to move around the cabin with relative ease. Typically taken to be a ceiling height of 5'8" or greater. Browse jets with stand-up cabins
STAR:  Standard Terminal Arrival Route, for inbound IFR traffic.
STATUTE MILEA unit of length equal to 5,280 feet.
STOL: Short Take-Off and Landing.
STOPOVER:  Scheduled interruption of a flight at an intermediate airport, either to refuel (in which case, it is known as a “technical stopover”) or to pick up/drop off PAYLOAD (for example: flight 789 from New York to Delhi, with a stopover in London). Unlike a connection, a stopover usually does not involve a change of flight number or airline, but may involve a change of aircraft.
STOVL:  Short Take-Off and Vertical Landing.
SUPER MID-SIZE JETSCombining transatlantic capability with the speed and comfort of a wide-body, high-altitude aircraft. Feature wide-body cabin space, high-altitude capability, speed and ultra-long range.
TACAN:  Tactical Air Navigation system. An ultra-high frequency electronic navigation aid which provides suitably-equipped aircraft with a continuous indication of bearing and distance to the selected Tacan station. The distance element can be received by civilian DME equipment, but otherwise Tacan is principally a military navaid.
TAIL NUMBERThe airplane’s registration number.
TAIL WINDWinds that come from behind the aircraft and provide additional air speed in flight.
TARMACA paved airport surface including runways or aprons at an aircraft hangar.
TAS: True Airspeed. Rectified airspeed corrected for altitude and outside air temperature.
TAWS(Terrain Awareness and Warning System) This system gives the flight crew earlier aural and visual warning of impending terrain. As an advanced type of GPWS, it also has forward looking capability and provides continued operation in the landing configuration.
TAXI TIMEThe time the aircraft is in transit to the runway up to the point of take off.
TCA(Terminal Control Area) A volume of controlled airspace set up at the confluence of airways in the vicinity of one or more major airports to protect traffic climbing out from and descending into the airports.
TCADThis proprietary low cost anti-collision system detects and alers pilots to nearby transponders. However, it does not provide evasive instructions or coordinate with other aircraft.
TCAS:  Traffic alert and Collision Avoidance System. U.S. developed radar-based airborne collision avoidance system operating independently of ground-based equipment. TCAS-I generates traffic advisories only, TCAS-II provides advisories and collision avoidance instructions in the vertical plane.
TECHNICAL STOP:Landing at an airport en-route to the destination airport for technical rather than operational reasons, most typically to upload fuel if the total journey exceeds the range of the aircraft.
THIRD PARTY VERIFICATIONRefers to the verification of safety, maintenance and operations by an independent auditor.
TOGA: Take-off/Go Around. An autopilot setting activating take-off or GO-AROUNDthrust.
TOUCHDOWN: Synonym of landing. May also refer to a stopover that does not involve a change of aircraft or flight.
TRACON:  Terminal Radar Approach Control. ATC for departures and approaches.
TRAFFIC PATTERNBased on a standard rectangular flight pattern around airport landing runways. May involve 45-degree or crosswind entry, with downwind, base and final legs as rectangle sides. 90-degree left turns are standard, while right-hand traffic patterns are considered non standard (noted in Airport Facility Directories). Downwind is usually flown at a 1,000 or 1,500 feet above the airport elevation. Those airports with a control tower may modify or short-cut the pattern under ATC instructions.
TRANSITION ALTITUDE (TA): Altitude in the vicinity of an aerodrome at or below which the vertical position of an aircraft is controlled by reference to altitude (with the aerodrome QNH set on its altimeter). Above transition altitude QNE is set and flight levels used. Also called transition level (TL) at which a descending aircraft changes from FL to QNH.
TRANSPONDER:  Airborne receiver/transmitter portion of the SSR system which receives the interrogation signal from the ground and automatically replies according to mode and code selected. Modes A and B are used for identification, using a four-digit number allocated by air traffic control. Mode C gives automatic altitude readout from an encoding altimeter.
TRUE AIR SPEEDThe speed of an aircraft relative to the airmass in which it is flying.
TSB:  Transportation Safety Board of Canada. Agency that investigates accidents, in a similar fashion to the NTSB in the United States or an AAIB in other countries.
TURBINEA vital component in jet engines, turbines use compressed air to generate thrust, and inside the motor, spin a metal shaft. Turbines also power turboprop aircraft.
TURBO JET AIRCRAFTSAircrafts with jet engines that operate turbines which operate air compressors.
TURBO PROP AIRCRAFTAn aircraft with turbine and propeller powered by a jet engine.
TURBO-PROP:An aircraft that has propellers driven by gas-turbine engines
TWR: Tower
TWY:  Taxiway
UHF:  Ultra-High Frequency. Radio frequencies in the 300-3,000 MHz band.
UM:  Unaccompanied Minor. Underage passenger (typically 5-15 years old) travelling without a parent, guardian or trusted adult. An UM is under the constant supervision of airline staff from the departure gate until he or she is picked up at the arrival airport.
UNICOM(UNIversal COMmunication) A common radio frequency (usually 121.0 mHz) used at controlled (non-tower) airports for local pilot communication. UNICOM is also used by a Fixed Base Operator for general administrative uses, including fuel orders, parking instructions, etc.
UPWIND: One of the many words describing the approach segments. See Final for a diagram.
UTC:Greenwich Mean Time (GMT). The abbreviation is a compromise between the French language term Temps Universel Co-ordonné and the English language equivalent Universal Co-ordinated Time.
V/STOL:  Vertical and Short Take-Off and Landing.
V1:  decision speed, up to which it should be possible to abort a take-off and stop safely within the remaining runway length. After reaching V1 the take-off must be continued.
VA:  design manoeuvring speed. The speed below which abrupt and extreme control movements are possible (though not advised) without exceeding the airframe’s limiting load factors.
VASIS:  Visual Approach Slope Indicator System. A colored light system providing visual guidance to the glidepath of a runway.
VFE: maximum flap extension speed (top of white arc on ASI).
VFR: Visual Flight Rules. Prescribed for the operation of aircraft in visual meteorological conditions (VMC). VMC is generally defined as 5 miles visibility or more and 1,000 feet vertical and one nautical mile horizontal clearance from cloud, but variations apply to aircraft operating below 3,000 feet AMSL. Special VFR (SVFR) clearances are granted at the discretion of ATC for VFR flight through some controlled airspace where IFR usually apply.
VHF: Very High Frequency. Radio frequencies in the 30-300 MHz band, used for most civil air-to-ground communication.
VIS:  Visibility
VISIBILITYThe ability to see and identify prominent un-lit objects during the day and lit objects of prominence at night.
VISUAL METEROLOGICAL CONDITIONSThe conditions in which pilots have enough visibility to fly an aircraft and maintain visual separation between clouds and a ceiling, terrain and other aircraft.
VLJVery Light Jet (may also be referred to as entry-level jet) is a small, short-range and jet that can be operated by a single pilot and seats 2-4 passengers.
VMCA:  minimum control speed (air). The minimum speed at which control of a twin-engined aircraft can be maintained after failure of one engine.
VMO: maximum operating speed. Also Mmo, Mach limit maximum operating speed.
VNAV:  Vertical Navigation
VNE:  never-exceed speed, ‘redline speed’ denoted by a red radial on an ASI.
VNO: normal operating speed. The maximum structural cruising speed allowable for normal operating conditions (top of green arc on ASI).
VOR:  Very high frequency Omnidirectional Range. A radio navigation aid operating in the 108-118 MHz band. A VOR ground station transmits a two-phase directional signal through 360°. the aircraft’s VOR receiver enables a pilot to identify his radial or bearing from/to the ground station. VOR is the most commonly used radio navigation aid in private flying. Increased accuracy is available in DVOR which have replaced some VORs in the UK system. Also VORTAC, combined VOR and TACAN, and VOT (VOR test facility).
VR: rotation speed, at which to raise the nose for take-off.
VSI:  Vertical Speed Indicator. One of the primary flight instruments showing rate of climb or descent.
VSO:  stalling speed at MTWA, in landing configuration with flaps and landing gear down, at sea level, ISA conditions (bottom of white arc on ASI).
VTOL:  Vertical Take-Off and Landing.
VX: best angle of climb speed on all engines.
VXSE: best engine-out angle of climb speed.
VY: best rate of climb speed on all engines.
VYSE:  best engine-out rate of climb speed, ‘blueline speed’ (blue radial on ASIS of light twin aircraft)
WACWorld Aeronautical Charts used for navigation, WACs are typically used by pilots operating aircraft at high altitudes and moderate speeds.
WAIT TIMEThe time the aircraft is waiting on the tarmac for the departure of its next leg of the itinerary.
WAKE TURBULENCETurbulent air condition caused by small, tornado-like horizontal whirlwinds trailing an aircraft's wingtips (wingtip vortices). Wake turbulence associated with larger aircraft flying at slow speeds (as on take-off or landing approach) is the most severe and can cause loss of control for smaller aircraft following close behind. Controllers use defined separation standards to avoid the problem for take-off, landing, approach and departure operations.
WAYPOINT: Reference point used for navigation, usually indicated by latitude and longitude and sometimes altitude and typically used for GPS and INS navigation.
WEATHER MINIMUMSThe lowest—or worst—visibility conditions an aircraft may be legally flown under visual flight rules. Aircraft are required to fly under instrument flight rules, or not at all, when visibility is less than the specified minimums.
WILLCO:  Will comply. See Roger.
WINDSHEAR:  localised change in wind speed and/or direction over a short distance, resulting in a tearing or shearing effect, usually at low altitude, that can cause a sudden loss of airspeed with occasionally disastrous results if encountered when taking-off or landing.
WINGLETUsed to improve fuel economy; a small rudder-like addition placed on the tips of a wing used to stabilize, control or employ air movement, thereby increasing fuel economy..
XMSN: Transmission
XPDR: Transponder
ZULUThe phonetic pronunciation of the final letter of the NATO phonetic alphabet.
ZULU TIME:UTC or Greenwich Mean Time (GMT). The aviation convention is to append the characters Z to times written as UTC and L to times written as local time. In the phonetic alphabet, Z is pronounced Zulu.