| 1 | KO | Alaska Central Express, Inc. | ICAO: AER, Callsign: Ace Air, | USA | AVCODES |
| 2 | KO | Aerolineas Colonia S.A. (Arco S.A.) | ICAO: AKO, Callsign: Kilo Oscar, | ROU | AVCODES |
| 3 | KO | Aircompany "KHORS" Ltd. | ICAO: KHO, Ceased operation. | UA | AVCODES |
| 4 | KO | Komiaviatrans Open Joint Stock Company | ICAO: KMA, Callsign: Komi Avia, Name changed from Komiaviatrans State Air Enterprise | RUS | AVCODES |
| 5 | KO | Kansas & Oklahoma R.R., Inc. | added 10/2001; 7/2005 | | NAKINA |
| 6 | KO | KANSAS & OKLAHOMA RAILROAD, INC. | | | PWRC |
| 7 | KO | Kansas and Oklahoma Railroad | | | RSRV |
| 8 | KO | KANSAS & OKLAHOMA RAILROAD INC | | | SCAC4 |
| 9 | KOA | Euro-Flite Oy Ltd. | | FIN | AVCODES |
| 10 | KOA | Koanda Avacion | | | ICAO1 |
| 11 | KOAC | KOOLATRON CORP | | | SCAC4 |
| 12 | KOAI | KOTA INC | | | SCAC4 |
| 13 | KOAL | KOCHNE, AL TRUCKING | | | SCAC3 |
| 14 | KOAS | KOBLE & SONS | | | SCAC3 |
| 15 | KOAX | Coca-Cola U.S.A. | eliminated 10/1987 | | NAKINA |
| 16 | KOAX | Coca-Cola U.S.A., a Division of The Coca-Cola Co. | added 4/1971; 1/1975-1/1980 | | NAKINA |
| 17 | KOAX | Coca-Cola U.S.A., a Division of The Coca-Cola Co. | added 4/71; 1/75-1/80 | | NRHS |
| 18 | KOAX | Coca-Cola U.S.A. | eliminated 10/87 | | NRHS |
| 19 | KOAX | COCA COLA USA | | | PWRC |
| 20 | KOAX | Coca-Cola | | | RSRV |
| 21 | KOB | Koob-Corp - 96 KFT | | | ICAO1 |
| 22 | KOBA | KOBAYASHI M TRUCKING | | | SCAC3 |
| 23 | KOBB | KOBBE HOWARD COMPANIA | | | SCAC3 |
| 24 | KOBE | KOBERLEIN EXPRESS & TRANSFER CO INC | | | SCAC3 |
| 25 | KOBE | KNOOPS FARM SERVICE INC | | | SCAC4 |
| 26 | KOBE | Kobe Municipial Transportation Bureau | City: Kobe | J | TRAFFIC |
| 27 | KOBF | KOBASHI FARMS INC | | | SCAC3 |
| 28 | KOBJ | KOBS, JERRY J INC | | | SCAC3 |
| 29 | KOBO | KOST BROTHERS INCORPORATED | | | SCAC3 |
| 30 | KOBSH | Kobe Electric Railway (Shintetsu) | | J | TRAFFIC |
| 31 | KOBT | KOBS, TERRY L TRUCK LINE | | | SCAC3 |
| 32 | KOBU | TER HAAK KOELBOX B.V. | | | SCAC3 |
| 33 | KOBW | KOBOW, KIM TRUCKING | | | SCAC3 |
| 34 | KOC | SetAir | Callsign: SetAir, | TR | AVCODES |
| 35 | KOCA | KOCAK TRUCKING COMPANY | | | SCAC3 |
| 36 | KOCA | KOCAK, J E TRUCKING AND TRANSPORTAT | | | SCAC4 |
| 37 | KOCG | KOCTUG DENIZCILIK VE TICARET | | | SCAC3 |
| 38 | KOCH | KOCH, DONALD M | | | SCAC3 |
| 39 | KOCI | KOCI, JERRY O | | | SCAC3 |
| 40 | KOCI | KOCSIS, HEATHER | | | SCAC4 |
| 41 | KOCM | KRANS OIL COMPANY INC | | | SCAC4 |
| 42 | KOCO | KERR OIL CO INC | | | SCAC4 |
| 43 | KOCQ | KALER OIL CO INC | | | SCAC4 |
| 44 | KOCS | KOCH SHIPPING INC | | | SCAC4 |
| 45 | KOCT | KOCH TRUCK LINE INC | | | SCAC3 |
| 46 | KOCU | KOBC CONTAINER LEASING NO. 1 LIMITED | | ROK | BIC |
| 47 | KOCV | KOCAK VAN LINES INC | | | SCAC3 |
| 48 | KOCV | KOCAK MOVING & STORAGE LLC | | | SCAC4 |
| 49 | KOCX | KEITH OIL CO | | | SCAC3 |
| 50 | KOCZ | KOCH REFINING COMPANY | | | PWRC |
| 51 | KODA | KODIAK TRANSFER, INC | | | SCAC3 |
| 52 | KODA | KODIAK TRANSFER COMPANY | | | SCAC4 |
| 53 | KODC | KING OCEAN SERVICES DE COLOMBIA S A | | | SCAC4 |
| 54 | KODI | KOERNER, D INC | | | SCAC3 |
| 55 | KODL | KODAI COMPANY LTD | | | SCAC4 |
| 56 | KODS | K O DELIVERY SERVICE | | | SCAC3 |
| 57 | KODU | KÖPPEN GMBH | | D | BIC |
| 58 | KOE | Northland Aviation, Inc. | Callsign: Kokee, | USA | AVCODES |
| 59 | KOE | Northland Aviation | | | ICAO1 |
| 60 | KOE | Klützer Ostsee Eisenbahn GmbH | Grevesmühlen | D | privat-bahn.de |
| 61 | KOE | Kurt König Baumaschinen GmbH | | DE | VKM |
| 62 | KOEA | KOEHN, ANDY | | | SCAC3 |
| 63 | KOED | KOELLER DRAYAGE CO | | | SCAC3 |
| 64 | KOEE | KONAL ENGINEERING & EQUIPMENT | | | SCAC4 |
| 65 | KOEF | KOEN, FLOYD TRUCKING | | | SCAC3 |
| 66 | KOEH | KOEHLER, KEN TRANSPORT | | | SCAC4 |
| 67 | KOEHNE | Koehne Gleisbau | | D | TRAFFIC |
| 68 | KOEI | KOREA OVERSEAS EXPRESS INC | | | SCAC4 |
| 69 | KOEN | KOENEN TRUCKING | | | SCAC4 |
| 70 | KOEP | KOEPPER MOVING & STORAGE INC | | | SCAC3 |
| 71 | KOEQ | KOEHL BROS INC | | | SCAC3 |
| 72 | KOEU | WALTER KÖLLNER GMBH SPEDITION | | D | BIC |
| 73 | KOFF | KRISTOFF TRUCKING | | | SCAC4 |
| 74 | KOFR | KING OF THE ROAD INC | | | SCAC3 |
| 75 | KOFV | KANOWSKY OF VIRGINIA INC | | | SCAC3 |
| 76 | KOG | Missouri Pacific System | eliminated 1/1980 | | NAKINA |
| 77 | KOG | Missouri Pacific Railroad Co. | added 1/1977; 1/1980 | | NAKINA |
| 78 | KOG | Texas and Pacific Railway Co. | 1/1975; eliminated 1/1977 | | NAKINA |
| 79 | KOG | Texas and Pacific Railway Co. | 1/75; eliminated 1/77 | | NRHS |
| 80 | KOG | Missouri Pacific Railroad Co. | added 1/77; 1/80 | | NRHS |
| 81 | KOG | Missouri Pacific System | eliminated 1/80 | | NRHS |
| 82 | KOG | UP [MISSOURI PACIFIC; TEXAS & PACIFIC RWY. CO.; KANSAS OKLAHOMA & GULF RY.] | | | PWRC |
| 83 | KOG | Kansas, Oklahoma and Gulf Railway (Union Pacific Railroad) | | | RSRV |
| 84 | KOG | Kansas, Oklahoma & Gulf | | USA | TRAFFIC |
| 85 | KOGH | KOTEK, GARY TRUCKING INC (HOURLY TR | | | SCAC4 |
| 86 | KOGL | K O CARTAGE LTD | | | SCAC3 |
| 87 | KOGO | KOTEK, GARY TRUCKING INC (ONE (1) W | | | SCAC4 |
| 88 | KOGR | KOGERS INC | | | SCAC4 |
| 89 | KOGT | KOTEK, GARY TRUCKING INC | | | SCAC3 |
| 90 | KOGWR | Zespół Elektrociepłowni Wrocławskich KOGENERACJA S.A. | | PL | VKM |
| 91 | KOHA | KOHEL FREIGHT SYSTEMS INC | | | SCAC4 |
| 92 | KOHB | KOHL BROS TRUCKING CO | | | SCAC3 |
| 93 | KOHD | KOCH, DANIEL E INC | | | SCAC3 |
| 94 | KOHE | KOEHLER, RANDY | | | SCAC3 |
| 95 | KOHE | KOHAR ENGINEERING | | | SCAC4 |
| 96 | KOHF | KOLWOOD HORSE FARMS INC | | | SCAC3 |
| 97 | KOHI | KOHLMAN INDUSTRIES LTD | | | SCAC3 |
| 98 | KOHL | KOHLER TRANSFER | | | SCAC3 |
| 99 | KOHO | KOHSHO INTERNATIONAL SERVICES LINE | | | SCAC3 |
| 100 | KOHO | KOHORST, DOUGLAS TRUCKING INC | | | SCAC4 |
