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Common Aviation
Acronyms, Abbreviations, Definitions and Jargon # A B C D E F G H I J K L M - - N O P Q R S T U V W X Y Z - Quotes - Airport Codes |
N ---------- back to the TopNATS - National Air Traffic Services. A division of the CAA providing UK air traffic control.NBAA - National Business Aircraft Association, USA. ND - Navigation Display. NDB - Mon-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 Mile. NOE - Nap of Earth. Low flying, usually by the military, using contour-flying techniques and terrain-masking to avoid being seen. NORDO - No Radio (used on flight plan form). NOSIG - No Significant Change, term used on Met reports. Notam - Notices to Airmen, issued by the CAA (and equivalent authorities elsewhere) to inform pilots of new or changed aeronautical facilities, services, procedures or hazards, temporary or permanent. Also SNOWTAM, a NOTAM concerning runway conditions in snow. NOTAR - No Tail Rotor. A system patented by McDonnell Douglas for maintaining directional control of helicopters without use of an anti-torque tail rotor. NPRM - Notice of Proposed Rule-Making (USA). Advance publication by the FAA of proposed changes or additions to Federal Air Regulations. NTSB - National Transportation Safety Board. U.S. equivalent of UK's AAIB. O ---------- back to the TopOAT - Outside Air Temperature. The temperature of the air outside an aircraft measured by a probe with a cockpit gauge readout. OAT affects the measurement of indicated airspeed and its value is needed to calculate true airspeed. At high speeds kinetic heating demands correction to the indicated OAT for true outside air temperature.OATS - Oxford Air Training School, a large commercial pilot training school at Oxford Airport, UK. OBS - Omni-Bearing Selector, part of a VOR used to select the radial from a VOR. OCH - Obstacle Clearance Height. The lowest height above the elevation of the runway threshold or above Airport elevation used to establish compliance with obstacle clearance criteria in an instrument approach. Also OCA, obstacle clearance altitude, and OCL, obstacle clearance limit. OEM - Original Equipment Manufacturer. okta - A measurement of cloud cover. One okta means one-eighth of the sky is covered. Omega - High accuracy, very-low frequency (VLF) long-range navigation system of the hyperbolic type, covering the entire earth down to the surface from eight ground-based transmitters. Used principally by airliners, military aircraft and intercontinental business aircraft. o/r - on request. o/t - other times. P ---------- back to the TopPan - International radio call signalling urgency.PAPI - Precision Approach Path Indicator, a system of coloured lights installed at the approach end of a runway which provides visual guidance to the correct glidepath. A successor to VASI, below. PAR - Precision Approach Radar. Primary radar equipment showing an air traffic controller the height, track and range of an aircraft on final approach, enabling him to guide it to a landing. PAX - Passengers. PFA - Popular Flying Association, the UK homebuilt and antique aircraft organisation. PFD - Primary Flight Display PIC - Pilot-In-Command (also styled P1). PINS - Pipeline Inspection Notification System. PIO - Pilot-Induced Oscillation. An undulating flight path brought about by over-controlling. PLN - Flight-Plan PMS - Performance management System PNF - Pilot Not Flying POB - (number of) Persons On Board. POC - Proof-Of-Concept. POH - Pilot's Operating Handbook, an aircraft's `owner's manual'. Pooley's - Annually-published flight guide to United Kingdom and Ireland, named after its creator and publisher Bob Pooley. PPL - Private Pilot's Licence. Also PPL(H) for helicopters, PPL(SLMG) for self-launched motor gliders. PPO - Prior Permission Only. Certain airfields or events require advance notification (by telephone, for example) of your intended arrival. Also PNR, prior notice required, and PPR, prior permission required. PROB - Probability Percentage, term used in Met reports. procedure turn - Manoeuvre which reverses the direction of an aircraft's flight during an instrument approach procedure to enable it to intercept the final approach course. psi - Pounds Per Square Inch, a measurement of pressure. PTT - Press-To-Transmit (switch) on an aircraft's control wheel or stick enabling the pilot to make RT transmission 'hands on' via a headset microphone. Purple Airspace - Special temporary airways created for flights by certain members of the royal family, notified by NOTAM. Q ---------- back to the TopQFI - Qualified Flying Instructor. Also QHI, Qualified Helicopter Instructor.Quadrantal Rule - System of cruising altitudes used in UK uncontrolled airspace below FL250. Q-code - Code system developed when air-to-ground communication was by wireless telegraphy, enabling many routine phrases and questions to be reduced to three letters. Now largely redundant, except these:
R ---------- back to the TopRabbit Lights - Colloquialism for sequentially flashing lead-in runway approach lights.Ramp Weight - Maximum permissible weight of an aircraft, which exceeds maximum take-off weight by an allowance for fuel burned during engine-start and taxi. RAPID - Change expected to take place in thirty minutes or less, term used in mer reports. RAS (1) - Rectified Airspeed. Indicated airspeed corrected for instrument position error. RAS (2) - Radar Advisory Service. Provided outside regulated airspace to notify pilots of conflicting traffic and to advise suitable avoiding action. Also RASA Radar Advisory Service Area. Rating - Add-on qualification to a pilot's licence, e.g. Night Rating, Multi-engine Rating, Instrument Rating, Seaplane Rating etc. Individual Type Ratings are necessary to fly aircraft over 12,500 pounds MTWA. RCL - Runway Center Line. RBI - Relative Bearing Indicator, displaying information from the ADF. RDO - Radio RIS - Radar Information Service. Provided to notify pilots of conflicting traffic outisde regulated airspace, but offering no avoiding action. 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. RMK - Remark(s). RMU - radio management unit. 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. RON - Remain Over Night (night-stop). RT - Radio Telephony. Voice communications, as opposed to WT, wireless telegraphy. Also styled RTF. RTA - Required Time Of Arrival. RVR - runway visual range, a horizontal measurement of visibility along a runway. RWY - Runway. Rx - Receiver. S ---------- back to the TopSACP - (CAA) Standing Advisory Committee on Pilot Licensing ( UK ).SAR - Search-and-Rescue. Also Sarsat, SAR satellite. SAS - Stability Augmentation System. An automatic flight control system employed in many helicopters and some fixed-wing aircraft to enhance their stability and handling qualities. SATCOMS - Satellite Communications, now being introduced on intercontinental airliners and business jets for (non- operational) air-to-ground voice communications via ground relay stations. SATNAV - Satellite Navigation SB - Service Bulletin. Advisory notices issued by aircraft, engine and equipment manufacturers alerting owners and engineers to faults or problems requiring preventitive or remedial maintenance or modification. Often termed `mandatory', but do not have the legal force of Airworthiness Directives (which see). SBAC - Society of British Aerospace Companies. The UK aerospace manufacturers' trade association. SDAU - Safety Data Analysis Unit of the CAA. `second pilot' - Unofficial term used to describe short (usually 8-10 hours) flying courses designed to enable non-pilot light aircraft passengers to take control and land in an emergency such as pilot incapacitation. Also standby or safety pilot and pinch-hitter (U.S.) Sectional - (U.S.) VFR navigation chart, equivalent to our 1:500,000 or `half-million'. Semi-circular - System of cruising altitudes. 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 bizjets. sfc - Specific fuel consumption of an engine, expressed in pounds of fuel consumed for each unit of power (hp, shp, lb/st) produced. Also surface. 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 - Warning of severe weather conditions (active thunderstorms, hail, severe turbulence, icing etc.) issued my Met offices. sl - Sea Level. SMOH - Since Major Overhaul. Term used in aircraft for sale advertisements where engine hours are quoted (see TBO). Also STOH, since top overhaul, TTSN, total time since new; TTAF/E, total time airframe/engine, SMR - Surface Movement Radar. SOB - Souls On Board, the number of persons on board an aircraft. Also POB. Socked-In - A colloquialism referring to an airport closed to air traffic by bad weather. SOP - Standard Operating Procedure. Specific Range - Measure of an aircraft's fuel efficiency, expressed as nautical miles flown per pound of fuel burned (nm/lb) SPL - Student Pilot's Licence. No longer issued in the UK, where a CAA medical certificate serves as an SPL. Squawk - To transmit an assigned code via a transponder (see SSR below). SR - Sunrise. SRZ - Special Rules Zone. An area of protected airspace surrounding an airfield and extending from the surface upwards to a specific level which affords safety to air traffic movements in the vicinity of airfields whose traffic level does not warrant the establishment of a Control Zone. Also SRA, Special Rules Area. extending vertically and horizontally from a level above the surface, but not necessarily terminating at the same upper level as the SRZ. SRA - Surveillance Radar Approach. Also Special Rules Area. SRE - Surveillance Radar Element of a GCA. SS - Sunset. SSB - Single Sideband. Reduction of bandwith by transmitting only one sideband and suppressing the other, and usually also the carrier wave. SSR - Secondary Surveillance Radar. A radar system comprising a ground-based transmitter/receiver which interrogates a compatible unit in the aircraft (see transponder below), providing instant radar identification without having to manoeuvre. Assigned four-digit transponder codes are referred to as squawk codes. STAB - Stabilizer. STAR - Standard Terminal Arrival Route, for inbound IFR traffic. STC - Supplemental Type Certificate. U.S. system for post-type certification approval of aircraft modifications such as re- engining, STOL kits, etc, where the full certification process is not deemed necessary. Also used by manufacturers to certify (often greatly changed) new models of old types under so-called `grandfather rights'. STOL - Short Take-Off and Landing. Also VTOL - Vertical Take-Off and Landing; V/STOL - Vertical/Short take-off and landing; STOVL - Short Take-Off, vertical landing. T ---------- back to the TopT - True.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 DMF equipment, but otherwise Tacan is principally a military navaid. TAF - Terminal Area Forecast. TAS - True Airspeed. Rectified airspeed corrected for altitude and outside air temperature. TBO - Time Between Overhauls, an engine manufacturer's recommended overhaul interval in hours, a rough and not guaranteed guide to life expectancy of an aero-engine before it will need overhaul. TCA - Terminal Control Area ( US ). 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. TDM - Track Detail Message. TEMPO - Temporarily THR - Threshold. TMA - Terminal Control Area. An area of controlled airspace at the intersection of airways in the vicinity of control zones (CTRs) around major airports. TO - Take-Off (sometimes TKOF). TODA - Take-Off Distance Available. Also TODR, take-off distance required, and TORA, take-off run available. Track - actual flight path of an aircraft over the ground. 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. Transition Altitude (TA) - altitude in the vicinity of an Airport at or below which the vertical position of an aircraft is controlled by reference to altitude, i.e. with the Airport QNH set on its altimeter. Above transition altitude QNE is set and flight levels used. Also transition level (TL) at which a descending aircraft changes from FL to QNH. Trend - Met forecast for the next two hours, added to some METARs. TSO - Technical Standard Order. A standard established by the U.S. FAA for quality control in avionics, instruments and other airborne equipment. If it complies, equipment is said to be 'TSO'd' and is more expensive than similar non-TSO's equipment. TVOR - terminal VOR. A low-powered VOR located at or near an airport and used as an approach aid. TWDL - Two Way Datalink. TWR - Tower (Airport control tower). TWY - Taxiway. Tx - Transmitter. U ---------- back to the TopUA - UnitedUAS - University Air Squadron. UDF - UHF Direction Finding. UFN - Until Further Notice. UHF - Ultra-High Frequency. Radio frequencies in the 300-3,000 MHz band. UHMRA - Upper Heyford Mandatory Radio Area. UIR - Upper Information Region, covering the same geographic areas as a FIR, but extending vertically upwards from 24,500 feet, within which certain additional operational rules apply. Also UIS, Upper Information Service. Unicom - Privately-operated advisory A/G radio service at uncontrolled airfields (USA). UNL - unlimited US - USAir u/s - Unserviceable (i.e not working) when applied to an aircraft or its equipment. USAF - United States Air Force UTC - Co-ordinated Universal Time (see also Zulu). V ---------- back to the TopV-speeds - Designations for certain velocities relating to aircraft operation, thus:
VAL - Visual Approach and Landing chart. var - Variation (magnetic) VASIS - Visual Approach Slope Indicator System. A coloured light system providing visual guidance to the glidepath of a runway. VDF - Very-High Frequency Direction Finding, whereby an aircraft's bearing from a ground receiving station may be determined from its RT transmissions. VFR - Visual Flight Rules. Prescribed for the operation of aircraft in visual meteorological conditions (VMC). VMC is generally defined as five 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. Also CVFR, Controlled VFR Flight. VHF - Very High Frequency. Radio frequencies in the 30-300 MHz band, used for most civil air-to-ground communication. VIS - Visibility. VLF - Very Low Frequency. Radio frequencies in the 3-30 kHz band. VLF/Omega - Worldwide system of long-range navigation using VLF radio transmission. VMC - Visual Meterorological Conditions. See VFR, above. Volmet - Continuous recorded broadcasts of weather conditions at selected airfields. 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 360ø. 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 Doppler VORs (DVOR) which have replaced some VOR is the UK system. Also VORTAC, combined VOR and TACAN, and VOT, VOR test facility. VP - Variable-Pitch (propeller), whose blade angle can be altered in flight either automatically or manually. VRP - Visual Reporting Point. Landmarks used for position reporting by aircraft operating VFR. V/S - Vertical Speed/Vertical VSI - Vertical Speed Indicator. One of the primary flight instruments showing rate of climb or descent. Also IVSI, instantaneous VSI. VTOL - Vertical Takeoff and Landing W ---------- back to the Topwake turbulence - wingtip vortices generated behind a wing producing lift. Behind a large heavy aircraft they can be powerful enough to roll or even break up a smaller aircraft.WAT - Weight-And-Temperature. w.e.f. - With Effect From Wind Shear - 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. WIP - Work In Progress. WP(T) - Waypoint. WT - Weight Wx - Weather. WX NIL - No significant weather, term used in Met reports. X ---------- back to the TopX-BAND - The frequency range between 8000 and 12500 MHz.xmsn - Transmission. XPDR - Transponder. Y ---------- back to the TopYD - Yaw DamperZ ---------- back to the Topzero-fuel weight - Maximum permissible weight of an aircraft beyond which an additional load must be in the form of fuel.zero-timed - Overhauling an aero-engine to 'service limits' (not the same `good as new' or factory remanufactured). Zulu - Worldwide times of flight operations. ---------- Back To The Top |