| GL | GRL | Air Greenland | GREENLAND | Greenland
Denmark |
| DBC | Gemini Air Group | DIAMOND BACK | United States | Allocated in 2014[1] |
| GCH | Gama Aviation Switzerland | GAMA SWISS | Switzerland |
| GX | GBC | Guangxi Beibu Gulf Airlines | SPRAY | China |
| GOP | Gospa Air | GOSPA AIR | Mexico |
| HGT | GMJ Air Shuttle | HIGHTECH | United States | Private air shuttle for Intel Corporation Employees |
| GRE | Greenlandcopter | Denmark |
| GMQ | Germania Express | CORGI | Germany |
| KNM | GB Helicopters | KINGDOM | United Kingdom |
| GCW | Global Air Crew | GLOBALCREW | Denmark |
| GBH | Global Avia Handling | Russia |
| Y5 | GMR | Golden Myanmar Airlines | GOLDEN MYANMAR | Myanmar |
| GML | G & L Aviation | GEEANDEL | South Africa |
| EXH | G5 Executive | BATMAN | Switzerland |
| MTA | GAK/Mitchell Aero | GAK AVIATION | United States |
| GGS | GATSA | GATSA | Mexico |
| GBX | GB Airlink | ISLAND TIGER | United States |
| GT | GBL | GB Airways | GEEBEE AIRWAYS | United Kingdom |
| GCS | GCS Air Service | GALION | United States |
| FFU | GEC Marconi Avionics | FERRANTI | United Kingdom |
| GCC | GECAS | GECAS | Ireland |
| GEN | GENSA | GENSA-BRASIL | Brazil |
| GET | Get High | AIR FLOW | Portugal |
| GET | GETRA | GETRA | Equatorial Guinea | ICAO Code no longer allocated |
| GFW | GFW Aviation | Australia |
| GGT | Trans Island Airways | THUNDERBALL | Bahamas |
| GHI | GH Stansted Limited | United Kingdom |
| Z5 | GMG | GMG Airlines | GMG | Bangladesh |
|
| GPE | GP Express Airlines | REGIONAL EXPRESS | United States |
| GPR | GPM Aeroservicio | GPM AEROSERVICIO | Mexico |
| GIB | GR-Avia | GRAVIA | Guinea |
| BMK | GST Aero Aircompany | MURAT | Kazakhstan |
| GTX | GTA Air | BIG-DEE | United States |
| GAH | Ga-Ma Helicoptere | GAMHELICO | France |
| GBE | Gabon Express | GABEX | Gabon |
| GRT | Gabon-Air-Transport | Gabon |
| GIG | Gacela Air Cargo | GACELA AIR | Mexico |
| GFC | Gail Force Express | GAIL FORCE | United States |
| GNJ | Gain Jet Aviation | HERCULES JET | Greece |
| SWF | Galair International | GALAIR | United Kingdom |
| GLS | Galaircervis | GALS | Ukraine |
| 7O | GAL | Galaxy Air | GALAXY | Kyrgyzstan |
| GXY | Galaxy Airlines | GALAX | Japan |
| GAS | Galena Air Service | GALENA AIR SERVICE | United States |
| 1G | Galileo International | United States |
| GMA | Gama Aviation | GAMA | United Kingdom |
| GC | GNR | Gambia International Airlines | GAMBIA INTERNATIONAL | Gambia |
| NML | Gambia New Millennium Air | NEWMILL | Gambia |
| GMJ | Gamisa Aviación | GAMISA | Spain |
| G7 | GNF | Gandalf Airlines | Gandalf | Italy |
| GAN | Gander Aviation | GANAIR | Canada |
| GSA | Garden State Airlines | GARDEN STATE | United States |
| AHM | Garrison Aviation | AIR HURON | Canada |
| GA | GIA | Garuda Indonesia | INDONESIA | Indonesia |
| GHS | Gatari Hutama Air Services | GATARI | Indonesia |
| EGO | Gauteng Air Cargo | GAUTENG | South Africa |
| GVN | Gavina | GAVINA | Spain |
| 4G | GZP | Gazpromavia | GAZPROMAVIA | Russia |
| GEE | Geesair | GEESAIR | Canada |
| GR | GCO | Gemini Air Cargo | GEMINI | United States |
| GAB | Gendall Air | GENDALL | Canada |
| GDB | Gendarmerie Belge | BELGIAN GENERMERIE | Belgium |
| FGN | National Gendarmerie | FRANCE GENDARME | France |
| SWK | General Aerospace | SKYWALKER | Canada |
| GWS | General Airways | GENAIR | South Africa |
| GNZ | General Aviation | GONZO | Poland |
| GTH | General Aviation Flying Services | GOTHAM | United States |
| XGA | General Aviation Terminal | Canada |
| GMC | General Motors | GENERAL MOTORS | United States |
| GNX | Genex | Belarus |
| GSL | Geographic Air Surveys | SURVEY-CANADA | Canada |
| A9 | TGZ | Georgian Airways | TAMAZI | Georgia |
| FGA | Georgian Aviation Federation | GEORGIA FED | Georgia |
| GGF | Georgian Cargo Airlines Africa | GEORGIAN AFRICA | Senegal |
| QB | GFG | Georgian National Airlines | NATIONAL | Georgia |
| Great Barrier Airlines | New Zealand | Not ICAO allocated - GBA issued for domestic use by the Civil Aviation Authority of New Zealand |
| GAF | German Air Force | GERMAN AIR FORCE | Germany |
| GAM | German Army | GERMAN ARMY | Germany |
| GNY | German Navy | GERMAN NAVY | Germany |
| GHY | German Sky Airlines | GERMAN SKY | Germany |
| ST | GMI | Germania | GERMANIA | Germany |
| 4U | GWI | Germanwings | GERMAN WINGS | Germany |
| GDN | Gerry's Dnata | Pakistan |
| GFD | Gesellschaft Fur Flugzieldarstellung | KITE | Germany |
| GP | RIV | APG Airlines | RIVERA | France |
| GES | Gestair | GESTAIR | Spain |
| GTR | Gestar | STAR GESTAR | Chile |
| GJT | Gestión Aérea Ejecutiva | BANJET | Spain |
| GHT | Ghadames Air Transport | Libya |
| GH | GLP | Globus Airlines | GLOBUS | Russia |
| GH | GHA | Ghana Airways | GHANA | Ghana | defunct |
| G0 | GHB | Ghana International Airlines | GHANA AIRLINES | Ghana |
| NTC | Gibson Aviation | NIGHT CHASE | United States |
| RPS | Global Air Charter | RESPONSE | United States |
| GAG | Greybird Pilot Academy | GEEBIRD | Denmark |
| GBS | Global Air Services Nigeria | GLOBAL SERVE | Nigeria |
| GLC | Global Aircargo | Bahrain |
| Global Airways (Turks and Caicos) | Turks and Caicos Islands |
| BSP | Global Airways (BSP) | Democratic Republic of Congo |
| GLB | Global Airways (GLB) | GLO-AIR | United States | Air Castle Corporation |
| GBB | Global Aviation Operations | GLOBE | South Africa |
| GAK | Global Aviation and Services Group | AVIAGROUP | Libya |
| GGZ | Global Georgian Airways | GLOBAL GEORGIAN | Georgia |
| GLJ | Global Jet Austria | GLOBAL AUSTRIA | Austria |
| NSM | Global Jet Corporation | THUNDERCLOUD | United States |
| SVW | Global Jet Luxembourg | SILVER ARROWS | Luxembourg |
| GSK | Global Sky Aircharter | GLOBAL SKY | United States |
| GSS | Global Supply Systems | JET LIFT | United Kingdom |
| XGS | Global System | United States |
| XGW | Global Weather Dynamics | United States |
| GLW | Global Wings | Japan |
| GJA | Globe Jet | Lebanon |
| G8 | GOW | GoAir | GOAIR | India |
| GK | Go One Airways | United Kingdom | Defunct? |
| G7 | GJS | GoJet Airlines | LINDBERGH | United States |
| GGE | Gobierno De Guinea Ecuatorial | Equatorial Guinea |
| GOF | Gof-Air | GOF-AIR | Mexico |
| GOI | Gofir | SWISS HAWK | Switzerland |
| G3 | GLO | Gol Transportes Aéreos | GOL TRANSPORTE | Brazil | Brazilian low-cost airline. |
| GBT | Gold Belt Air Transport | GOLD BELT | Canada | defunct |
| GDA | GoldAir | AIR PARTNER | United Kingdom |
| GDK | Goldeck-Flug | GOLDECK FLUG | Austria |
| DC | GAO | Golden Air | GOLDEN | Sweden |
| GDD | Golden Airlines | GOLDEN AIRLINES | United States |
| GPA | Golden Pacific Airlines | GOLDEN PAC | United States |
| GRS | Golden Rule Airlines | GOLDEN RULE | Kyrgyzstan |
| GLD | Golden Star Air Cargo | GOLDEN STAR | Sudan |
| GOS | Goldfields Air Services | Australia |
| GAQ | Golfe Air Quebec | GOLFAIR | Canada |
| GLE | Goliaf Air | GOLIAF AIR | São Tomé and Príncipe |
| GOM | Gomel Airlines | GOMEL | Belarus |
| 5Z | GON | Gonini Air Services | GONINI | Suriname | defunct |
| RDR | Goodridge (UK) Limited | RED STAR | United Kingdom |
| G1 | Gorkha Airlines | GORKHA AIRLINES | Nepal | ?ICAO |
| GOR | Gorlitsa Airlines | GORLITSA | Ukraine |
| HKG | Government Flying Service | HONGKONG GOVERNMENT | Hong Kong SAR of China |
| GRZ | Government of Zambia Communications Flight | COM FLIGHT | Zambia |
| HLD | Grampian Flight Centre | GRANITE | United Kingdom |
| GAV | Granada Aviación | GRANAVI | Spain |
| GAE | Grand Aire Express | GRAND EXPRESS | United States |
| GND | Grand Airways | GRAND VEGAS | United States |
| CVU | Grand Canyon Airlines | CANYON VIEW | United States |
| GV | GUN | Grant Aviation | HOOT | United States |
| LMK | Grantex Aviation | LANDMARK | United Kingdom |
| GRA | Great American Airways | GREAT AMERICAN | United States | Defunct |
| GRA | Guardian Air Assest Management | FLEX | South Africa | issued in 2017 |
| ZK | GLA | Great Lakes Airlines | LAKES AIR | United States |
| GLU | Great Lakes Airways (Uganda) | LAKES CARGO | Uganda |
| GRP | Great Plains Airlines | GREAT PLAINS | United States |
| IJ | GWL | Great Wall Airlines | GREAT WALL | China |
| GWA | Great Western Air | G-W AIR | United States |
| HAF | Hellenic Air Force | HELLENIC AIR FORCE | Greece |
| HNA | Greek Navy | HELLENIC NAVY | Greece |
| GFF | Griffin Aviation | GRIFFIN AIR | Cyprus |
| GXA | Grixona | GRIXONA | Moldova |
| GZD | Grizodubova Air Company | GRIZODUBOVA AIR | Russia |
| HTG | Grossmann Air Service | GROSSMANN | Austria |
| GSJ | Grossmann Jet Service | GROSSJET | Czech Republic |
| GHV | Ground Handling Service de Mexico | GROUND HANDLING | Mexico |
| GPM | Grup Air-Med | GRUPOMED | Spain |
| EJC | Grupo De Aviación Ejecutiva | GRUPOEJECUTIVA | Mexico |
| TAT | Grupo TACA | TACA-COSTARICA | Costa Rica |
| VMM | Grupo Vuelos Mediterraneo | VUELOS MED | Spain |
| GMT | Grupo Aéreo Monterrey | GRUPOMONTERREY | Mexico |
| GSY | Guard Systems | GUARD AIR | Norway |
| G6 | BSR | Guine Bissaur Airlines | BISSAU AIRLINES | Guinea-Bissau |
| GIJ | Guinea Airways | GUINEA AIRWAYS | Guinea |
| GNC | Guinea Cargo | GUINEA CARGO | Equatorial Guinea |
| J9 | GIF | Guinee Airlines | GUINEE AIRLINES | Guinea | defunct |
| GEA | Guinea Ecuatorial Airlines | GEASA | Equatorial Guinea |
| GIQ | Guinee Paramount Airlines | GUIPAR | Guinea |
| CGH | Guizhou Airlines | GUIZHOU | China |
| GUS | Guja | GUJA | Mexico |
| G8 | GUJ | Gujarat Airways | GUJARATAIR | India |
| TSU | Gulf & Caribbean Cargo / Contract Air Cargo | TRANSAUTO | United States |
| GUF | Gulf African Airlines | GULF AFRICAN | The Gambia |
| GF | GFA | Gulf Air | GULF AIR | Bahrain |
| GAT | Gulf Air Inc | GULF TRANS | United States |
| GCN | Gulf Central Airlines | GULF CENTRAL | United States |
| SFY | Gulf Flite Center | SKY FLITE | United States |
| GPC | Gulf Pearl Air Lines | AIR GULFPEARL | Libya |
| GLF | Gulfstream Aerospace | GULFSTREAM TEST | United States |
| GFS | Gulfstream Airlines | GULFSTAR | United States |
| GFT | Gulfstream International Airlines | GULF FLIGHT | United States |
| GUL | Gull Air | GULL-AIR | United States |
| GUM | Gum Air | GUM AIR | Suriname |
| GDH | Guneydogu Havacilik Isletmesi | RISING SUN | Turkey |
| GY | Guyana Airways 2000 |
| GWN | Gwyn Aviation | GWYN | United Kingdom |
| GAC | GlobeAir | DREAM TEAM | Austria |
| 3S | GUY | Air Guyane Express | GREEN BIRD | French Guyana |