| 1 | KT | Kampuchea Airlines | ICAO: KMP, Callsign: Kampuchea, Designator KT recalled by IATA | K | AVCODES |
| 2 | KT | Birgenair | ICAO: BHY, Callsign: Birgenair, Ceased operatons | TR | AVCODES |
| 3 | KT | British Airtours Ltd. | ICAO: BKT, Callsign: Beetours, ICAO designator changed to CKT / Name changed to Caledonian Airways | GB | AVCODES |
| 4 | KT | Turtle Airways Ltd. | ICAO: TLT, Callsign: Turtle, Designator KT recalled by IATA | FJI | AVCODES |
| 5 | KT | Caledonian Airways Limited | ICAO: CKT, Callsign: Caledonian, IATA dsignator changed to KG | GB | AVCODES |
| 6 | KT | Kyrgyz Air | ICAO: KAF, Callsign: Ak Shoumkar, Designator KT recalled by IATA | KS | AVCODES |
| 7 | KT | BEA Airtours Ltd. | Callsign: Beatours, Name change to British Airtours Ltd. | GB | AVCODES |
| 8 | KT | Katmai Air LLC | | USA | AVCODES |
| 9 | KT | Public JSC Kharkiv Airlines | ICAO: KHK, Callsign: Sunray, IATA dsignator changed to KW | UA | AVCODES |
| 10 | KT | SiAvia, d.o.o. | ICAO: SVB, Callsign: Siavia, Designator KT recalled by IATA | SLO | AVCODES |
| 11 | KT | Mahogany Air Charters | ICAO: HOG, Callsign: Hogan Air, Suspended operations in 2014. | Z | AVCODES |
| 12 | KT | FlyGLO, LLC | Flights operated by Corporate Flight Management, Inc - ICAO VTE. Suspended operations on 15 July 2017. | USA | AVCODES |
| 13 | KT | Kentucky & Tennessee Ry. Co. | 4/1938-1/1980; eliminated 10/1993; 1/1994-7/2005 (not listed) | | NAKINA |
| 14 | KT | Kentucky & Tennessee Ry. Co. | 4/38-1/80; eliminated 10/93; 1/94-7/2000 | | NRHS |
| 15 | KT | KENTUCKY & TENNESSEE RAILWAY CO. | | | PWRC |
| 16 | KT | Kentucky and Tennessee Railway | | | RSRV |
| 17 | KT | Karelian Trains | Oy Karelian Trains Ltd was a joint venture agreed on 23 November 2006 between Russian Railways (RZhD) and VR Group (Finnish Railways) to facilitate the operation of international express passenger rail services between Helsinki, Finland, and Saint Petersburg, Russia. | FIN | TRAFFIC |
| 18 | KT | OY Karelian Trans Ltd | | FI | VKM |
| 19 | KTA | Kirov State Avia Enterprise | Callsign: Vyatka-Avia, | RUS | AVCODES |
| 20 | KTA | K2 Airways | Callsign: City Link, | PK | AVCODES |
| 21 | KTA | Kirov Air Enterprise | | | ICAO1 |
| 22 | KTAC | KNIGHT MOTOR FREIGHT, INC | | | SCAC3 |
| 23 | KTAD | KANAB TAXI AND DELIVERY | | | SCAC3 |
| 24 | KTAG | KG TRANSIT INC | | | SCAC4 |
| 25 | KTAI | KINGSWAY TRANSPORT OF AMERICA, INC | | | SCAC3 |
| 26 | KTAI | KINGSWAY (DIV OF TFI TRANSPORT 5) | | | SCAC4 |
| 27 | KTAJ | KHALSA TRANSPORTATION | | | SCAC4 |
| 28 | KTAM | KENT TRANS-AMERICAS CLOTHING CORP | | | SCAC3 |
| 29 | KTAQ | KATAUSKAS, ALEX | | | SCAC3 |
| 30 | KTAQ | K & A TRUCKING CO | | | SCAC4 |
| 31 | KTAR | KARTAR TRUCKING LTD | | | SCAC4 |
| 32 | KTAS | KENNEDY TRANSPORTATION | | | SCAC4 |
| 33 | KTAT | KEITA TRANSPORTATION | | | SCAC3 |
| 34 | KTAT | KDM TRANSPORT LTD | | | SCAC4 |
| 35 | KTAV | KW TRUCKING | | | SCAC4 |
| 36 | KTAW | KAMAL TRANSPORT | | | SCAC4 |
| 37 | KTB | UAB AK, Transaviabaltika | Callsign: Transbaltika, | LT | AVCODES |
| 38 | KTB | Transaviabaltika | | | ICAO1 |
| 39 | KTB | Zweckverband Kandertalbahn | | DE | VKM |
| 40 | KTBA | KOLSTAD TANK & BULK AGENCY INC, HAR | | | SCAC3 |
| 41 | KTBB | KORTH TRUCKING INC | | | SCAC4 |
| 42 | KTBG | KING TRANSPORT | | | SCAC4 |
| 43 | KTBH | KTB TRUCKING CO | | | SCAC4 |
| 44 | KTBI | KST TRANSPORT | | | SCAC4 |
| 45 | KTBJ | KINGSTON TRANSPORTATION LLC | | | SCAC4 |
| 46 | KTBK | KULLANGI TRANSPORTATION & BROKERAGE | | | SCAC4 |
| 47 | KTBL | KITCHEN, B L TRANSPORTATION | | | SCAC4 |
| 48 | KTBO | KALIJAH TRANSPORT | | | SCAC4 |
| 49 | KTBR | K T L INC | | | SCAC4 |
| 50 | KTBT | KENT BROS TRANSPORTATION | | | SCAC3 |
| 51 | KTBV | KEVCO TRUCKING INC | | | SCAC4 |
| 52 | KTC | Kyrgyz Trans Avia Ltd. Airline | IATA: 6K, Ceased operations. | KS | AVCODES |
| 53 | KTC | Kyrgyz Trans Avia | | | ICAO1 |
| 54 | KTCC | KAYCO TRUCKING CO INC | | | SCAC3 |
| 55 | KTCF | KELLEY TRUCKING COMPANY LLC | | | SCAC4 |
| 56 | KTCG | KENYA TRUCKING COMPANY LLC - KENATC | | | SCAC4 |
| 57 | KTCH | KITCHELL, JOAN | | | SCAC3 |
| 58 | KTCH | KITCHENS M R S INC | | | SCAC4 |
| 59 | KTCI | KTC INC | | | SCAC3 |
| 60 | KTCK | KTC INC | | | SCAC3 |
| 61 | KTCL | KONOIKE TRANSPORTATION CO. LTD. | | | SCAC3 |
| 62 | KTCL | KELLEY TRANSIT COMPANY | | | SCAC4 |
| 63 | KTCM | KENNTORR TRUCKING COMPANY LLC | | | SCAC4 |
| 64 | KTCO | KETCO TRUCKING CO INC | | | SCAC3 |
| 65 | KTCO | K T C T | | | SCAC4 |
| 66 | KTCP | KIMOLOS TANKER CORPORATION | | | SCAC4 |
| 67 | KTCQ | KENTON TRANSFER CO | | | SCAC3 |
| 68 | KTCQ | KIRBY TRANS CORP | | | SCAC4 |
| 69 | KTCR | K-T CONTRACT SERVICES INC | | | SCAC3 |
| 70 | KTCR | KTC | | | SCAC4 |
| 71 | KTCS | KITCHUCK & SON | | | SCAC3 |
| 72 | KTCS | K-T CONTRACT SERVICES | | | SCAC4 |
| 73 | KTCT | K T C TRANSPORT INC | | | SCAC3 |
| 74 | KTCT | KATCO TRANSPORT INC | | | SCAC4 |
| 75 | KTCU | AEROSOL GAS COMPANY, INC | | USA | BIC |
| 76 | KTCU | KUSKOKWIM TRANSPORTATION CO. | | | SCAC3 |
| 77 | KTCV | KITTU TRANSPORT INC | | | SCAC4 |
| 78 | KTCW | KNOWLES TRUCKING COMPANY INC | | | SCAC4 |
| 79 | KTCX | Klamath Gas Co. | added 7/1963; 7/1965-1/1975; eliminated 1/1980 | | NAKINA |
| 80 | KTCX | Klamath Gas Co. | added 7/63; 7/65-1/75; eliminated 1/80 | | NRHS |
| 81 | KTCX | KLAMATH GAS CO. | | | PWRC |
| 82 | KTCX | KLAMATH GAS CO | | | SCAC3 |
| 83 | KTCY | KEMP TRUCKING COMPANY INC | | | SCAC4 |
| 84 | KTDA | KALKAVAN TRANSPORT DENIZCILIK A S | | | SCAC4 |
| 85 | KTDC | KENT TRADING CORP. | | | SCAC3 |
| 86 | KTDG | K & T DISTRIBUTING | | | SCAC3 |
| 87 | KTDH | KHATAU TRANSPORT LTD | | | SCAC4 |
| 88 | KTDL | KAPCO TOOL & DIE LTD | | | SCAC4 |
| 89 | KTDU | CONDACO & KTD-M GMBH | | D | BIC |
| 90 | KTDU | KTD MOBILBOX GMBH | | | SCAC4 |
| 91 | KTEP | K-T EXPRESS INC | | | SCAC3 |
| 92 | KTER | Kingston Terminal R.R. Corp. | added 7/1980; eliminated 10/1980 | | NAKINA |
| 93 | KTER | Kingston Terminal R.R. Corp. | added 7/80; eliminated 10/80 | | NRHS |
| 94 | KTER | KINGSTON TERMINAL RAILROAD CORP. | | | PWRC |
| 95 | KTER | KINGSTON TERMINAL RAILROAD CORP | | | SCAC3 |
| 96 | KTEU | SHARK, S.A | | P | BIC |
| 97 | KTEZ | KOC CARBON TERMINAL | | | PWRC |
| 98 | KTFC | KTF TRANSPORT INC | | | SCAC4 |
| 99 | KTFI | KING TRANSFER & STORAGE COMPANY INC | | | SCAC3 |
| 100 | KTFM | KITLEY, TROY FARMS | | | SCAC4 |
