A
A           Aircraft (JAR-FCL License)
A           Airspace ICAO Class A
A/C         Aircraft NOTE: plural form of "aircraft" takes no "s": aircraft
A/G         Air/Ground (Air to ground and v.v.)
AAIM        Aircraft Autonomous Integrity Monitoring
ABAS        Aircraft Based Augmentation System
ACARS       Aircraft Communications Addressing and Reporting System
ACAS        Airborne Collision Avoidance System
ACC         Area Control Center
ACG         ATM/CNS Consulting Group (Eurocontrol)
ACI         Airport Council International
ACT         active, activated, activation message
AD          Aerodrome
AD          Airworthiness Directive
ADB         Airports Database
ADCUS       Advise customs
ADD         Architecture Description Document
ADF         Automatic Direction Finder
ADIZ        Air Defence Identification Zone
ADLP        Airborne Data Link Processor
ADS         Automatic Dependent Surveillance
ADS-A       Automatic Dependent Surveillance-Address
ADS-B       Automatic Dependent Surveillance-Broadcast
ADS-C       Automatic Dependent Surveillance-Contract
AEA         Association of European Airlines
AECMA       Association of European Aerospace Industries
AFB         Air Force Base
AFIS        Aerodrome Flight Information Service
AFM         Aeroplane Flight Manual
AFTN        Aeronautical Fixed Telecommunication Network
AGA         Aerodromes and Ground Aids (AIP)
AGATE       Advanced General Aviation Transport Experiments (NASA)
AGDL        Air-Ground Data Link
AGL         Above Ground Level
AGLO        Arbeitsgruppe Luftraum-Organisation
AIC         Aeronautical Information Circular
AIM         ATFM Information Message
AIM         Aeronautical Information Manual (AIP in USA)
AIM         Aeronautical Information Management (Eurocontrol)
AIP         Aeronautical Information Publication
AIRAC       Aeronautical Information Regulation and Control
AIS         Aeronautical Information Service
ALT         Altitude
ALTN        Alternate
ALTP        Airline Transport Pilot(s Licence)
AMC         Acceptable Means of Compliance
AMC         Airport Movement Control (Zurich)
AMC         Airspace Management Cell
AME         Aero Medical Examiner (FAA, JAA)
AME         Aircraft Maintenance Engineer (Australia)
AMIE        AIS Met Information Equipment (Swiss Computer Self Briefing System)
AMS         Aero Medical Services
AMSL        Above mean sea level
ANM         ATFM Notification Message
ANR         Air Navigation Routes
ANS         Active Noise System
ANS         Air Navigation Services
ANSP        Air Navigation Service Provider
ANT         Airspace Navigation Team (Eurocontrol)
AO          Aircraft Operator
AOC         Airline Operations Centre
AOPA        Aircraft Owners and Pilots Association
AoR         Aeroa of Responsibility
AOWIR       Aircraft Operator What-If Reroute (CFMU/IFPS)
APP         Approach (Control)
ARCID       Aircraft Identification
ARINC       (former Aeronautical Radio Inc., now just) ARINC (Manufacturer/Standard Setter)
ARN         ATS Route Network
ARNS        Aeronautical Radio Navigation Services
ARO         Air Traffic Services Reporting Office (or Airport Reporting Office)
ARP         Airport Reference Point
ARR         Arrival
ASAP        As soon as possible
ASAS        Airborne Separation Assurance system
ASF         Air Safety Foundation (AOPA-USA)
ASM         Air Space Management
ASPH        Asphalt Runway
ATA         Actual Time of Arrival
ATC         Air Traffic Control
ATCO        Air Traffic Control Officer
ATD         Actual Time of Departure
ATD         ATC and Data Processing (EATMP Unit)
ATE         Actual Time Enroute
ATFM        Air Traffic Flow Management
ATIR        Air Traffic Incident Report ("Near-Miss Report")
ATIS        Automatic Terminal Information Service
ATM         Air Traffic Management
ATN         Aeronautical Telecommunication Network
ATPL        Airline Transport Pilot ('s Licence)
ATS         Air Traffic Services
ATSP        Air Traffic Service Provider
AVGAS       Aviation Gasoline (piston aircraft fuel)
AWY         Airway
B
B           Airspace ICAO Class B
BABLW       Bundesamt für Betriebe der Luftwaffe
BAZL        Bundesamt für Zivilluftfahrt (Swiss CAA)
BBJ         Boeing Business Jet 
BDY         Boundary
BEF         Before
BFR         Biennial Flight Review (USA)
BFU         Büro für Flugunfalluntersuchungen
BRNAV       Basic RNAV (RNP-5 compliant)
BSE         Bovine Spongiform Encephalopathy (or: mad cow desease)

C
C           Airspace ICAO Class C
C           Celsius (Centigrade)
C(-Office)  Crew Office (AIS/MET)
CAA         Civil Aviation Authority (of a country)
CAPS        Complete Aircraft Parachute System
CAS         Calibrated Air Speed
CASA        Civil Aviation Safety Agency (CAA in Australia)
CASA        Computer Assisted Slot Allocation
CAT         Commercial Air Traffic
CAT         Commercial Air Transport
CAT         Clear-Air Turbulence
CAT I       Instrument Landing Category I (similar: CAT II, CAT III)
CARD II     CNS Applications Research & Development
CAVOK       Ceiling and Visibility ok (good VFR weather)
CB          Cumulonimbus
CBA         Cost-Benefit Analysis
CDA         Continuous Descent Approach
CDI         Course Deviation Indicator
CDM         Collaborative Decision-Making
CDR         Conditional Route (FUA)
CDTI        Cockpit Display of Traffic Information
CEAC        Conférence Européenne de l'Aviation Civile (see ECAC)
CFI         Certified Flight Instructor (USA)
CFII        Certified Flight Instructor IFR (USA)
CFIT        Controlled Flight Into Terrain
CFMU        Central Flow Management Unit of Eurocontrol
CG          Center of Gravity
CH          Compass Heading
CHF         Swiss Francs (Bankers' code)
CIA         CFMU Internet Application
CILO        Capacity Increase LOwer airspace
CIV         Civil
CLR         Clearance (or cleared)
CLSD        Closed
CMIC        Civil Military Interface standing Committee
CNS         Communication Navigation Surveillance
CNS/ATM     Communication Navigation Surveillance/Air Traffic Management
CoA, CofA   Certificate of Airworthiness
CODA        Central Office for Delay Analysis (Eurocontrol)=
COM         Communications
COPI        Co-Pilot
CPDLC       Controller-Pilot DataLink Capability (or Communications)
CPL         Commercial Pilots Licence
CR          Class Rating
CRAM        Conditional Route Availability Message 
CRCO        Central Route Charge Office of Eurocontrol
CRE         Class Rating Examiner
CRI         Class Rating Instructor
CRM         Cockpit Resource Management
CRS         Conditional Route System (FUA: "Temporary Airways" on request)
CTAF        Common Traffic Advisory Frequency
CTR         Control Zone
CU          Cumulus
CUST        Customs
CVFR        Controlled VFR (still existing in some countries)
CVR         Cockpit Voice Recorder
D
D           Airspace ICAO Class D
DA          Decision Altitude
DAP         Downlink Aircraft Parameter (Mode S Transponder)
dB          Decibel
DC          Dual Control
DCA         Directorate of Civil Aviation
DCT         direct
DEG         Degrees
DEL         Delay/delayed
DEP         Departure
DEV         Deviation
DF          Direction Finder
DFS         Deutsche Flugsicherung AG
DG          Director General (or: Direction Générale e.g. EU)
DG          Directional Gyro (Gyro Compass)
DGNSS       Differential GNSS
DGPS        Differential GPS
DGTren      Directorate General Transport and Energy (EU)
DH          Decision Height
DLA         Delay (Message of an ICAO FPL)
DME         Distance Measuring Equipment
DOF         Date of Flight
DOP         Dilution of Precision (GPS)
DP          Data Processing
DSP         Digital Signal Processor
DUAT        Direct User Access Terminal (US Computer Self-Briefing system)
E
E           East
E           Airspace ICAO Class E
EAA         Experimental Aircraft Association
EAD         European AIS Database
EAG         European ATFM Advisory Group
EANPG       European Air Navigation Planning Group (ICAO)
EAS         European Air Sports
EASA        European Aviation Safety Authority (planned to replace JAA)
EATCHIP     European Air Traffic Control Harmonization Implementation Project
EATMS       European Air Traffic Management System
EATMP       European Air Traffic Management Plan
EBAA        European Business Aviation Association
EC          European Commission
ECAC        European Civil Aviation Conference ("Association" of Europe's CAAs)
ECOGAS      European Council of General Aviation Support
EEC         Eurocontrol Experimental Centre
EET         Estimated Elapsed Time
EFATO       Engine Failure At Take-Off (JAR-FCL)
EFDP        European Flight Data Processing
EFIS        Electronic Flight Instrumentation System
EGNOS       European Geostationary Navigation Overlay System
EHS         Enhanced Surveillance (Mode S, 2nd step)
EHSI        Electronic Horizontal Situation Indicator
ELBA        Emergency Locator Beacon-Aircraft
ELEV        Elevation
ELT         Emergency Locator Transmitter (crash-activated transmitter)
EMC         EATMP Management Committee
ENPRM       Eurocontrol (European?) Notice of Proposed Rule Making
EOBT        Estimated off-block time
EP          European Parliament
ERA         European Regional Airlines Association
ESA         European Space Agency
ESC         Economic Social Committee
ETA         Estimated Time of Arrival
ETD         Estimated Time of Departure
ETFMS       Enhanced Tactical Flow Management System
ETSI        European Telecommunication Standardizatio Institute
ETOPS       Extended Range Twin-Engine Operations (or: Engines Turn Or Passengers Swim)
EU          European Union
EUAPA       European Union Airplane Pilots Association
EUR         European Region
EUR         Euro (currency)
EUROCAE     European Organisation for Civil Aviation Equipment
F
F           Airspace ICAO Class F
F           Fahrenheit
FA          Area Forecast (Meteo)
FAA         Federal Aviation Administration
FADEC       Full Authority Digital Engine Control
FAF         Final Approach Fix
FAWP        Final Approach Waypoint
FANS        Future Air Navigation System (an ICAO project group)
FAR         Federal Aviation Regulation (+Number)
FBO         Fixed Base Operator
FCC         Federal Communications Commission (USA)
FCL         Flight Crew Licensing
FCM         Flight Confirmation Message
FD          Winds and Temperature aloft Forecast
FDP         Flight Data Processing
FDR         Flight Data Recorder
FE          Flight Examiner
FI          Flight Identity (Code) - (Mode S Transponder)
FI          Flight Instructor
FIC         Flight Information Center
FIE         Flight Instructor Examiner
FIO         Flight Information Office
FIR         Flight Information Region
FIS         Flight Information Service
FIS-B       Flight Information Service-Broadcast
FFAS        Free Flight Air Space (Eurocontrol Definition)
FL          Flight Level, Altitude x100 = feet AMSL (FL 70 = 7000ft) at ISA
FLIR        Forward Loocking Infra-Red
FLOS        Flight Level Orientation System
FLT         Flight
FM          Frequency Modulation
FMD         Flow Management Division (CFMU/Eurocontrol)
FMP         Flow Management Position (local Slot coordinator)
FMS         Flight Management System
FNPT        Flight Navigation and Procedure Trainer
FOCA        Federal Office for Civil Aviation (Swiss CAA - see BAZL)
FOD         Foreign Object Damage
FPL         Flight Plan (for ATC)
fpm         feet per minute (vertical speed)
FSDM        Flight Statistical Development Management
FSDO        Flight Standard District Office (FAA USA)
FSS         Flight Service Station
ft          feet (approx 0.3 Meters)
FTD         Flight Training Device (lower category "simulator")
FTO         Flight Training Organisation (Flight School)
FUA         Flexible Use of Airspace
FVS         Fliegerische Vor-Schulung
G
G           Acceleration force unit (1G = Earth Gravity)
G           Airspace ICAO Class G
GA          General Aviation (mainly private and business aviation)
GA&AW GA/AW General Aviation and Aerial Work (all non-commercial civil aviation)
GAC         General Aviation Center
GAFOR       General Aviation Forecast (Weather)
GAL         Gallons (usually US 3.78 liter, may be Imperial 4.54 liter)
GAMA        General Aviation Manufacturers Association (USA)
GAT         General Air Traffic
GAT         General Aviation Terminal
GATT        General Agreement on Trade and Taxes
GBAS        Ground Based Augmentation System (DGNSS/DGPS/LAAS)
GCA         Ground Controlled Approach ("Talk-down")
GCI         Ground Communication Infrastructure
GEN         General
GENDEC      General Declaration Customs Form see full size, download zipped form, 
GEO         Geostationary Earth Orbit (Satellite)
GEO         geographic (NAV: versus magnetic)
GFT         General Flight Test (JAR-FCL)
GHz         Gigahertz (1'000 MHz or 1'000'000'000 Hertz)
GLD         Glider
GLONASS     Global Orbitting Navigation Satellite System (Russian GNSS)
GLS         GPS Landing System
GM-P10      GM=Morocco, P10=Prohibited Area No. 10. 
GND         Ground
GNSS        Global Navigation Satellite System (Satellite Navigation in General)
GPA         Groupe Parlementaire pour l'Aviation
GPH         Gallons (US) per hour
GPS         Global Positioning System (USA GNSS), see also FAA GPS Product Team
GPWS        Ground Proximity Warning System
GRAS        GBAS Regional Augmentation System
GS          Ground Speed
GSC         Global Signalling Channel (VDL-4)
GSM         General Standard for Mobile Communication (Mobile phones)
H
H           Helicopter (JAR-FCL)
HB-         Swiss nationality marks for aircraft registration
hPa         Hecto-Pascal. Unit to measure pressure (e.g. weather reports)
HDG         Heading
HEL         Helicopter
HEO         High Earth Orbit
HF          High Frequency
Hg          Mercury (Unit for pressure measurement inHg etc.)
HIGE        Hover In Ground Effect
HIRL        High Intensity Runway Lights
HITS        Highway In The Sky (Flight/NAV display concept)
HJ          Operating hours during daylight
HMI         Human Machine Interface
HOGE        Hover Out of Ground Effect
HOL         Holidays (MON-TUE-WED-THU-FRI-SAT-SUN-HOL)
HP          Horsepower
HQ          Headquarters
HSI         Horizontal Situation Indicator
HUD         Head-Up Display
HX          Operating hours on request
H24         Operating 24 hours
I
IACA        International Air Charter Association
IAF         Initial Approach Fix
IAOPA       International Council of Aircraft Owner and Pilot Associations
IAOPA-EUR   IAOPA European Region
IAS         Indicated Air Speed
IAS-TFB     Implementation Air Space Task Force Group B (Eurocontrol)
IATA        International Air Transport Association
IAWP        Initial Approach Waypoint
IC          Interogator Codes (II and SI codes)
ICAO        International Civil Aviation Organisation (a UN-Suborganisation)
ICD         Interface Control Document
ID          Identification
IDL         Interface Definition Language
IFPS        Integrated Flightplan Processing System of Eurocontrol
IFPUV       IFPS Validation System (offline Route Verification by Internet) 
IFR         Instrument Flight Rules ("all" weather operations rules)
IG(al)      Imperial Gallon (4,54 Liter)
II          Interogator Identity (Code) - (Mode S Transponder)
ILS         Instrument Landing System
IM          Inner Marker
IMC         Instrument Meteo Conditions (weather requiring IFR flight)
in          inch
inHg        inches of Mercury (unit of pressure)
INS         Intertial Navigation System
IPG         IFR Procedure Group
IPPL        National (ICAO) Private Pilots License (AOPA internal abbreviation)
IR          Instrument Rating
IR          Infra Red
IRE         Instrument Rating Examiner
ISA         ICAO Standard Atmosphere          ) Both definitions exist. 
ISA         International Standard Atmosphere ) Unclear which one is corrct!
ITU         International Telecommunication Union
J
JAA         Joint Aviation Authorities (CAA of Europe)
JAR         Joint Aviation Recommendation (as used in some JAA documents, reported false!)
JAR         Joint Aviation Regulation (as used in some JAA documents, reported false!)
JAR         Joint Aviation Requirement
JAR-1       JAR on Definitions and abbreviations
JAR-22      JAR on Sailplanes and and Powered Sailplanes
JAR-25      JAR on Large Airplanes
JAR-36      JAR on Aircraft Noise
JAR-145     JAR on Approved Maintenance Organisations
JAR-147     JAR on Maintenance Training
JAR-APU     JAR on Auxiliary Power Units
JAR-AWO     JAR on All Weather Operations
JAR-E       JAR on Engines
JAR-FCL     JAR on Flight Crew Licensing
JAR-MED     JAR on Medical
JAR-P       JAR on Propellers
JAR-TSO     JAR on Technical Standard Orders
JAR-OPS     JAR on Flight Operations
JAR-VLA     JAR on Very Light Aeroplanes
JET-A1      Jet Fuel type A1
JPPL        JAR-FCL Private Pilots License (AOPA internal abbreviation)
JSA         Joint Steering Assembly (JAA)
JURG        Joint User Requirement Group
K
K           Airspace Eurocontrol Project Class K (all traffic known)
kHz         Kilohertz (1'000 Hertz)
KIAS        knots indicated air speed
KOSIF       Koordinationsstelle für Schiess-Informationen (Swiss MIL Shooting)
KPI         Key Performance Indicator
kph         Kilometers per hour
KTAS        knots true air speed
kt(s)       knots (1.852 km/h)
L
LAAS        Local Area Augmentation System
LAHSO       Land And Hold Short Operation (to cross intersecting runway)
LAT         Latitude
LBA         Luftfahrt-Bundes-Amt (German CAA)
lbst        Pounds of static thrust
LDA         Landing Distance Available
LDG         Landing
LEO         Low Earth Orbit
LH          Lefthand
LI-R5       LI=Italy, R5=Restricted Area No. 5
LIRL        Low Intensity Runway Lights
LLWAS       Low Level Wind Shear Alert System
LLZ         Localizer (approach system)
LNAV        Lateral Navigation (GLS)
LOA, LoA    Letter of Agreement
LOC         Local, Location, Localizer
LONG        Longitude
LORAN(-C)   Long Range Navigation
LSC         Local Signalling Channel (VDL-4)
LS-D12      LS=Switzerland, D12=Danger Area No. 12
LT          Local Time
LTE         Long Term Exception (JAR-FCL)
M
MAC         Mean Aerodynamic Chord
MAHWP       Missed Approach Holding Waypoint
MAP         Map section of AIP
MAS         Managed Airspace (Eurocontrol Definition for ATM2000+)
MAS UAC     Maastricht Upper Airspace Center
MASP        Minimum Aviation System Performance
MATSE       ECAC Transport Ministers Meeting on the Air Traffic System in Europe
MATZ        Military ATZ
MAUW        Maximum All-Up Weight
MAWP        Missed Approach Waypoint
mb          Millibar (replaced by hPa)
MCC         Multi-Crew Certificate (JAR-FCL)
MCI         Mobile Communication Infrastructure
MCTR        Military CTR
MD          Medical Doctor
MDA         Minimum Descent Altitude
ME          Multi Engine
MEA         Minimum Enroute Altitude
MEL         Minimum Equipment List
MEL         Multi-Engine Land
MEO         Medium Earth Orbit
MEP         Member of Parliament
MEP         Multi Engine Piston
MET         Meteo (office, report, service etc.)
METAR       Meteorological Actual Report (current weather)
MFD         Multi Function Display
MH          Magnetic Heading
MHP         Menthal Health Professional (or: psychologist)
MHz         Megahertz (1'000 kHz)
MIL         Military
MLS         Microwave Landing System
MLW         Maximum Landing Weight
MM          Middle Marker
MMI         Man-Machine Interface (see HMI)
MMR         Multi-Mode Receiver
MNPS        Minimum Navigation Performance Specifications
MOCA        Minimum Obstacle Clearance Altitude
MOD         Moderate
MOGAS       Motor Gasoline (Auto-Gas)
MON         Motor Octane Number (aviation fuel rating)
MON         Monday (MON-TUE-WED-THU-FRI-SAT-SUN-HOL)
MOPS        Minimum Operation Performance Standards
MOT         Ministry of Transport
MP          Multi-Pilot
MPA         Multi-Pilot Aeroplane
MPH         Multi-Pilot Helicopter
mph         Miles per hour (statute miles, 1.609 km/h)
MRVA        Minimum Radar Vector Altitude
MRW         Maximum Ramp Weight
MSA         Minimum Safe Altitude
MSG         Message
MSL         Mean Sea Level
MT          Magnetic Track
MTOM        Maximum Take-Off Mass
MTOW        Maximum Take-Off Weight
MVA         Minimum Vectoring Altitude
MZFW        Maximum Zero-Fuel Weight
M$          Megadollars (1'000'000 US dollars)
N
N           Airspace Eurocontrol project Class N (managed traffic only)
N           North
n/a         not available or not applicable
N(....)     Country identifier for aircraft registered in USA
NAA         National Aviation Authority (generic term within JAA)
NABS        Navigation Augmentation Broadcast Service (ICAO for GBAS)
NASA        National Aeronautics and Space Agency (USA)
NAT         North Atlantic
NATO        North Atlantic Treaty Organisation
NATS        National Air Traffic Service (UK)
Navaid      Navigation Aid (Ground Radio Station for Navigation)
NAV         Navigation
NDB         Non Directional Beacon
NEAN        North European ADS-B Network
NELS        Northwest Europe Loran Steering Committee
NIMBY       "Not In My Back-Yard"-Syndrome: "We need an airport but not here"
NIL         Nothing, no information
NM, nmi     Nautical Mile (1.852 km)
NOSAR       No Search and Rescue required (Australia)
NOTAM       Notice to Airmen
NOTAR       No Tail Rotor
NPA         Non-Precision Approach
NPA         Notice of Proposed Ammendment (JAR)
NPO         Non-Profit Organisation
NPPL        National (ICAO) Private Pilots License (AOPA internally used: IPPL)
NPRM        Notice of Proposed Rule-Making (USA)
NTSB        National Transport Safety Board (USA)
NVFR        Night VFR
NW          North-west
O
O/R         on request
OACI        Organisation de l'Aviation Civile Internationale (voir ICAO)
OAT         Outside Air Temperature
OAT         Operational Air Traffic (MIL)
OBS         Omni Bearing Selector (VOR)
OBST        Obstacle, obstruction
OCD         Operational Concept Document
ODIAC       Operational Development of Initial Air/ground Data Communications
ODT         Operational Requirements and Data Processing Systems Team
OFAC        Office Fédérale de l'Aviation Civile (Swiss CAA - voir BAZL)
OM          Outer Marker
OMS         Outer Marker Substitute (sort of a virtual OM)
ONC         Operational Navigation Chart
OPS         Operations (or Operating hours)
ORD         Operational Requirments Document
            
P
p/p         per person, per passenger
PANS        Procedures for Air Navigation Services (ICAO)
PAPI        Precision Approach Path Indicator
PAR         Precision Approach Radar
PART        Pressure Altitude Reporting Transponder
PAX         Passenger(s)
PCL         Pilot Controlled Lighting (RWY Lights operated by Microphone)
PED         Personal Electronic Devices (e.g. Walkman, Handy etc.)
PETAL       Preliminary Eurocontrol Trial Air/ground Data Link
PGL         Parlamentarische Gruppe für Luftfahrt
PiC         Pilot in Command
PIREP       Pilot (weather) Report
PNR         Prior Notice Required
POB         Persons on Board
PP(L)       Private Pilots Licence (general)
PPL A       Private Pilots Licence Aeroplane
PPL H       Private Pilots Licence Helicopter
PPL/IR      Association of PPL holders with Instrument Rating
ppm         Parts Per Million
PPM         Possible Pricing Mechanism (Eurocontrol)
PPM         Programme Portfolio Management
PPO         Prior Permission Only
PPP         Public Private Partnership
PPR         Prior Permission Required
PRC         Performance Review Commission (Eurocontrol)
PRK         Photo Refractory Keratomy (eye surgery)
PRNAV       Precision RNAV (RNP-1 or less compliant)
PRR         Performance Review Report
PSG         Program Steering Group
PSI         Pounds per square inch
PSIA        Plan Sectoriel d'Infrastructure A‚ronautique
PT          Procedure Turn
PVT         private
Q
QDR         (Q-Code) for Homing Track from a Station
QDM         (Q-Code) for Homing Track to a Station
QGO         (Q-Code) for Airport Closed
QFE         (Q-Code) for Air Pressure in hPa on Ground (airport elevation)
QNH         (Q-Code) for Air Pressure in hPa calculated to MSL
QUAMGO      Quasi-Monopoly Government Organisation
R
R           Rating
R&D         Research and Development
RA          Resolution Advisory (TCAS)
RAF         Royal Air Force
RAIM        Receiver Autonomous Integrity Monitoring
RB          Relative Bearing (NAV)
RBAS        Receiver Based Augmentation System (DGNSS/DGPS)
RCA         Recommended Crossing Altitude
RCA         Remote Client Application (CFMU)
REA         Ready Message
REIL        Runway End Identifier Lights
RF          Radio Frequency
RF          Registered Facility ("national" flight school as per JAR-FCL)
RFI         Request For Improvement Message (slot)
RFP         Reglement über die Ausweise für das Flugpersonal
RH          Righthand
RIA         Regulatory Impact Assessment
RIMS        Remote Integrity Monitoring Station (?)
RM          Regional Meeting
RMI         Radio Magnetic Indicator
RMK         Remark(s)
RNAV        Area Navigation
RNP         Radio Navigation Plan
RNP         Required Navigation Performance 
RNP-n       accuracy of +/- n NM during 95% of flight must be maintained
RNSS        Radio Navigation Satellite Services
ROC         Rate of Climb
RON         Research Octane Number (Auto fuel rating)
RON         Remain Over Night
RPL         Repetitive Flight Plan
RPM         Revolutions per Minute
RPN         Réglement pour le Personnel Navigant
RPPL        Restricted PPL
RSO         Route per State Overflown
RTCA        (formerly) Radio Technical Commission for Aeronautics, now RTCA Inc.
RT(F), R/T  Radio Telephony
RTA         Remote Terminal Access (CFMU)
RUSC        RVSM User Support Cell
RVR         Runway Visual Range
RVSM        Reduced Vertical Separation Minima (1000ft above FL 290)
RW, RWY     Runway
RxTx        Receiver-Transmitter
S
s/n         serial number
SAR         Search and Rescue
SARP        Standards And Recommended Practices (usually "Sarps" =plural form)
SAT         Saturday (MON-TUE-WED-THU-FRI-SAT-SUN-HOL)
SAT         Satellite ...
SATNAV      Satellite Navigation (generic)
SB          Service Bulletin
SBAS        Space (or Satellite) Based Augmentation System (DGNSS/DGPS/WAAS/EGNOS)
SC          Stratocumulus
SE          Single-Engine
SEL         Single-Engine Land
SEP         Single-Engine Piston
SFC         Surface
SFE         Synthetic Flight Examiner 
SG          Sub-Group (of Eurocontrol Working Groups)
SI          Surveillance Identity (Code) - (Mode S Transponder)
SID         Standard Instrument Departure
SIGMET      Significant Meteo (hazardous weather warning)
SIM         Simulator
SIL         Sachplan Infrastruktur Luftfahrt
SIP         Slot Improvement Proposal Message
SIRO        Simultaneous Intersecting Runway Operation
SITA        Société Internationale de Télécommunication Aéronautique
SL          Sea Level
SLP         Speed Limit Point
SM          Statute Mile (1.609 km -  ACHTUNG: Nicht See-Meile!)
SME         Small and Medium Enterprises
SMEL        Single/Multi Engine Land
SMGCS       Surface Movement Guidance and Control System
SMGS        Surface Movement Guidance System
SMM         Slot Missed Message
SMS         Short Message System (Mobile Telephone Feature)
SMS         Surface Management System
SP          Single Pilot
SPA         Single Pilot Aeroplane
SPA         Slot Improvement Proposal Acceptance Message
SPECI       Special Report (Meteo)
SPH         Single Pilot Helicopter
SPIC        Student Pilot in Command (JAR-FCL)
SR          Sunrise
SRJ         Slot Improvement Proposal Rejection Message
SRR         Slot Revision Request Message
SRS         Standard Routing Scheme (ARN)
SS          Sunset
SST         Slot Start Time
SST         Super Sonic Transport
STA         Scheduled Time of Arrival
STAR        Standard Arrival
STC         Supplemental Type Certificate
STD         Scheduled Time of Departure
STD         Synthetic Training Device
STDMA       Self-Organizing Time Division Multiple Access (VDL)
SUA         Special Use Airspace (USA)
SUN         Sunday (MON-TUE-WED-THU-FRI-SAT-SUN-HOL)
SVFR        Special VFR
SWC         Significant Weather Chart
SWIM        System Wide Information Management
SWM         SIP Wanted Message
T
t / T       tonne
t/o         take-off
TA          Transition Altitude
TACAN       Tactical Air Navigation
TACT        Tactical System (CFMU)
TAF         Terminal Area Forecast (weather forecast)
TAS         True Air Speed
TAWS        Terrain Awareness and Warning System
TBO         Time between overhaul
TC          True Course
TCAS        Traffic alert and Collision Avoidance System
TCH         Threshold Crossing Height
TDMA        Time Division Multiple Access (VDL)
TF          Task Force
TGL         Technical Guidance Leaflet (JAA)
TH          True Heading
THR         Threshold
TIM         Time (Eurocontrol, everybody else is able to add an "e")
TIS-B       Traffic Information System-Broadcast
TKOF        Take-Off
TLS         Transponder Landing System
TMA         Terminal (Control) Area
TMG         Touring Motor Glider
TNC         Tactical Navigation Chart
TPIA        Transition Plan for Implementation of Airspace Strateby
TPC         Tactical Piloting Chart
TSMO        Time since major overhaul
TSO         Technical Standard Order
TR          Type Rating
Transeiver  Transmitter-Receiver
Transponder Transmitter-Responder
TRE         Type Rating Examiner
TRI         Type Rating Instructor
TRTO        Type Rating Training Organisation
TT          Total Time (since new or since ...)
TT          True Track
TWR         Tower (Control Tower)
U
U           Airspace Eurocontrol project Class U (unknown traffic)
u/s         unserviceable
UAT         Universal Access Transceiver
UAV         Unmanned (or Uninhabited) Aeronautical (or Aerial) Vehicle
UFN         Until Further Notice
UFO         Unidentified Flying Object
UHF         Ultra High Frequencies (300 MHz-30 GHz)
UL, ULM     Ultralight, Ultra-léger motorisé
UMAS        Unmanaged Air Space (Eurocontrol Definition)
URB         User Relations Bureau (CFMU)
USAF        US Air Force
USG(al)     US-Gallon (3.78 Liter)
UTC         Universal Time Coordinated
           
V
V           Speeds (see box for details)
VAL         Visual Approach and Landing (Chart)
VAR         Variation
VASI        Visual Approach Slope Indicator
VAT         Value Added Tax
VDB         VHF Data Broadcast
VDL         VHF Data Link (-n = type n)
VFR         Visual Flight Rules ("good" weather operations rules)
VHF         Very High Frequency (30-300 MHz)
VIS         Visual, Visibility
VJAR-FCL    Verordnung JAR-FCL (JAR-FCL transformed to Swiss Law)
VLA         Very Light Aircraft (Aircraft certification category)
VLA         Very Large Aircraft (NATO description for future transport aircraft)
VMC         Visual Meteo Conditions ("good" weather for VFR or IFR)
VNAV        Vertical Navigation (GLS)
VOR         VHF Omnidirectional Radio-Range
VORTAC      VOR/TACAN Station (combined)
VOR/DME     Combined VOR and DME radio station
W
WA          (IAOPA) World Assembly
WAAS        Wide Area Augmentation System
WCA         Wind Correction Angle
WGS-84      World Geodetic System of 1984
WIP         Work in Progress
WMO         World Meteorological Organisation
WP, WPT     Waypoint
WWII        2nd World War
WX          Weather
X
XPDR        Transponder. Radar-enhancement/datalink box for ATC purposes.
Y
Y2k        Year-2000 (computer date problem) 
           NOTE: k=decimal kilo=1000 (1-1000); thus Y2k=2000
                 K=binary kilo=1024 (0-1023); thus Y2K=2047
Z

Z          Zulu Time (=UTC)
0—9
100/130    AVGAS of 100 (best mixture)/130 octane (full rich mixture)
100LL      AVGAS of 100 (best mixture)/130 octane (full rich) low lead (=most used)
1090       Mode S Transponder (1090 MHz = Mode S Frequency)
406 MHz    Emergency Locater Beacon (or Transmitter) on 406 MHz Frequency
4D (NAV)   4-Dimensional Navigation (LONG LAT ALT TIME)
5 by 5     Five by five is an expression used in aviation (and maybe other) 
           radio communication to indicate the quality and loudness of received voice 
           transmissions. Rated one to five indicates - first figure - clearness and - 
           second - loudness. Five by five means that a transmission is received clear 
           and loud (in clear words usually loud and clear is used...). One by one, on 
           the other hand, means it can hardly be heard and is not understandable. If 
           you have a loud but distorted transmission, you may hear two by five, and a 
           weak but clearly understandable one may be called five by three... The 
           definition of this must be included somewhere in a radiotelephony document 
           of ICAO (International Civil Aviation Organisation) 
8.33 (kHz) Communication Frequences with 8.33 kHz channel spacing
80/87      AVGAS of 80 (best mixture)/87 octane (full rich mixture)
82UL       AVGAS of 82 (best mixture) octane (approx 90 octane full rich) unleaded
91/96UL    AVGAS of 91 (best mixture)/96 octane (full rich mixture) unleaded
V-Speeds

VAManoeuvering Speed (max. structural speed allowed for full control deflection)
VDMax. Dive Speed (for certification only)
VFEMax. Flaps Extended Speed
VLEMax. Landing Gear Extended Speed
VLOMax. Landing Gear Operation Speed
VNENever Exceed Speed
VNOMax. Structural Cruising Speed
VRRotation Speed
VS0Stalling Speed Landing Config.
VS1Stalling Speed in a specified Config.
VSSEMinimum Safe Single Engine Speed
VXBest Angle of Climb Speed
VXSEBest Angle of Climb Speed, 1 engine inoperative
VYBest Rate of Climb Speed
VYSEBest Rate of Climb Speed, 1 engine inoperative
 
Voice Spelling Alphabet ALFA BRAVO CHARLY DELTA ECHO FOXTROTT GOLF HOTEL INDIA JULIET KILO LIMA MIKE NOVEMBER OSCAR PAPA QUEBEC ROMEO SIERRA TANGO UNIFORM VICTOR WHISKY X-RAY YANKEE ZULU ONE TWO T(H)REE FOUR FIVE SIX SEVEN EIGHT NINER ZERO HUNDRED T(H)OUSAND DECIMAL (POINT)
EXAMPLES:
129.05
100
2000
2570
10000
25700
Echo X-ray Alfa Mike Papa Lima Echo Sierra.
ONE TWO NINER DECIMAL ZERO FIVE
ONE HUNDRED
TWO THOUSAND
TWO FIVE SEVEN ZERO
ONE ZERO THOUSAND
TWO FIVE THOUSAND SEVEN HUNDRED
 
AIRSPACE
ICAO CLASS Rules of use and services Remarks
A IFR: full separation.
VFR: not allowed
 
B IFR: full separation.
VFR: full separation. Reduced minimum distance from clouds. Clearance required.
 
C IFR: full separation.
VFR: separation from IFR. Traffic info VFR as far as practicable. Clearance required.
 
D IFR: full separation.
VFR: separation from IFR. Entry clearance and permanent radio contact required.
 
E IFR: separation IFR/IFR, Traffic info VFR as far as possible.
VFR: unrestricted. Information/SAR service.
 
F IFR: advisories and traffic info as far as practicable
VFR: unrestricted. Information/SAR service.
 
G IFR: information/SAR service
VFR: information/SAR service
 
REMARKS 1. Speed limits below 10000ft: 250kts. Reduced visibility 5km
2. A-E = controlled airspace, F/G = uncontrolled airspace
 

 
FPL Codes

Equipment Codes to be used in FPL

NAV/COM/APP

SUR/CAP

Letter current use proposed use Letter current use proposed use
A   RNAV A XPDR Mode A XPDR Mode A
B   FMS single B    
C LORAN-C LORAN-C C XPDR Mode A+C XPDR Mode A+C
D DME DME D ADS ADS
E   FMS dual E FMS  
F ADF ADF F    
G GPS GNSS G GNSS  
H HF HF H    
I INS (?) INS I    
J Datalink Datalink J    
K   MLS K MLS  
L ILS ILS L    
M MMR MMR M    
N no equipment   N    
O VOR VOR O    
P   GPS P    
Q Glonass Glonass Q    
R RNAV   R(n) RNP RNP n=1+9
S     S(n) XPDR Mode S XPDR Mode S n=1+9
T TACAN TACAN T(n) ACAS ACAS n=1+9
U UHF UHF U    
V VHF VHF V(n) RVR RVR n=1+9
W     W RVSM RVSM
X     X MNPS  
Y   8.33kHz Y 8.33kHz  
Z other equipment   Z other equipment