| 1 | KU | Kuwait Airways | ICAO: KAC, Callsign: Kuwaiti, IATA Prefix: 229, ICAO designator changed from Kilo Uniform. | KWT | AVCODES |
| 2 | KU | Kuwait Airways | ICAO: KAC, Callsign: Kilo Uniform, IATA Prefix: 229, ICAO designator changed to Kuwaiti | KWT | AVCODES |
| 3 | KUA | Kaua Transportes Aereos, S.A. de C.V. | Callsign: Transportes Kaua, | MEX | AVCODES |
| 4 | KUAN | KUEHNE & NAGEL INC | | | SCAC3 |
| 5 | KUAN | KURRLE TRANSPORT INC | | | SCAC4 |
| 6 | KUANG | Kuo-Kuang Motor Transportation | | RC | TRAFFIC |
| 7 | KUANGHUA | Kuanghua Bus | | RC | TRAFFIC |
| 8 | KUB | Florian Mencle | | DE | VKM |
| 9 | KUBC | KUBACH CARTAGE INC | | | SCAC3 |
| 10 | KUBC | KUBACH CARTAGE INC | | | SCAC4 |
| 11 | KUBFM | Florian Mencle | | DE | VKM |
| 12 | KUBIKI | Kubiki Railway & Bus | | J | TRAFFIC |
| 13 | KUBL | KUBLY, FRANK J, TRANSFER, INC | | | SCAC3 |
| 14 | KUBO | KURZ, CHAS CO | | | SCAC3 |
| 15 | KUBQ | KUBINSKI, HARRY B | | | SCAC3 |
| 16 | KUBQ | KES EXPRESS TRUCKING INC | | | SCAC4 |
| 17 | KUBR | KUHNLE BROTHERS INC | | | SCAC3 |
| 18 | KUBR | KUHNLE BROTHERS INC | | | SCAC4 |
| 19 | KUBT | KUB TRANSPORT | | | SCAC4 |
| 20 | KUBU | KUBE & KUBENZ INT. SPEDITION-UND | | D | BIC |
| 21 | KUBU | KUBE & KUBENZ INT SPEDITION GES | | | SCAC4 |
| 22 | KUCH | KOUKLIS CUSTOM HARVESTING | | | SCAC3 |
| 23 | KUCH | KUESEL TRUCKING LLC | | | SCAC4 |
| 24 | KUCI | KUPERUS TRUCKING INC | | | SCAC3 |
| 25 | KUCI | KUPERUS TRUCKING INC | | | SCAC4 |
| 26 | KUCO | KURTZ, CLAUDE D | | | SCAC4 |
| 27 | KUCX | Kentucky Utilities Co. | added 7/1976; 1/1980; eliminated 4/1991; added 10/1992; 1/1994-7/2005 | | NAKINA |
| 28 | KUCX | Kentucky Utilities Co. | added 7/76; 1/80; eliminated 4/91; added 10/92; 1/94-7/2000 | | NRHS |
| 29 | KUCX | KENTUCKY UTILITIES COMPANY | | | PWRC |
| 30 | KUCX | Kentucky Utilities | | | RSRV |
| 31 | KUCX | KENTUCKY UTILITIES COMPANY | | | SCAC4 |
| 32 | KUD | Kudu Air Services Limited | Callsign: Kudu, | Z | AVCODES |
| 33 | KUD | Kudos Aviation Ltd. | Callsign: Air Kudos, | GB | AVCODES |
| 34 | KUD | KEOKUK UNION DEPOT | | | PWRC |
| 35 | KUDE | KNUDSEN ENGINEERING LIMITED | | | SCAC4 |
| 36 | KUDK | KUDICK STANDARD | | | SCAC3 |
| 37 | KUDO | KUDOS TRANSPORTATION INC | | | SCAC4 |
| 38 | KUDR | KUDAMATSU, ROBERT | | | SCAC3 |
| 39 | KUDS | KUDO SHIPPING CO LTD | | | SCAC3 |
| 40 | KUDT | KNUDSEN TRUCKING INC | | | SCAC3 |
| 41 | KUDT | KNUDSEN TRUCKING INC | | | SCAC4 |
| 42 | KUDU | GATEWAY CONTAINER SALES & HIRE PTY LTD | | AUS | BIC |
| 43 | KUDU | GATEWAY CONTAINER SALES & HIRE PTY | | | SCAC4 |
| 44 | KUEB | KUEHN BROS INC | | | SCAC3 |
| 45 | KUEB | KENYON AUTO CENTRE LTD | | | SCAC4 |
| 46 | KUEH | KUEHNS TRUCKING | | | SCAC3 |
| 47 | KUEI | KUEHNLEIN TRUCKING INC | | | SCAC4 |
| 48 | KUEJ | KUJAK, E & J & T TRUCKING INC | | | SCAC3 |
| 49 | KUEK | KUEKER, HAROLD | | | SCAC3 |
| 50 | KUEQ | KUECHLE TRUCKING SERVICE | | | SCAC3 |
| 51 | KUET | KUEHNOW TRUCKING INC | | | SCAC3 |
| 52 | KUFL | KUFAHL TRUCKING INC | | | SCAC3 |
| 53 | KUFQ | KAUFFMAN, JAKE & SON INC | | | SCAC3 |
| 54 | KUFS | KAUAI FREIGHT SERVICE | | | SCAC3 |
| 55 | KUFS | KAUAI FREIGHT SERVICE INC | | | SCAC4 |
| 56 | KUG | Government of Kuwait | Callsign: Kuwaiti Gov, | KWT | AVCODES |
| 57 | KUGA | Kumagawa Railway | | J | TRAFFIC |
| 58 | KUGL | KUGLER OIL COMPANY | | | SCAC4 |
| 59 | KUGR | KUGKAKLIK LTD | | | SCAC3 |
| 60 | KUGS | KUHN, G & SONS TRUCKING | | | SCAC3 |
| 61 | KUGT | KRUG TRUCKING | | | SCAC3 |
| 62 | KUGW | KUGLER, GEORGE W, INC | | | SCAC3 |
| 63 | KUH | Kush Aviation Co. Ltd. | Callsign: Kush Aviation, | SUD | AVCODES |
| 64 | KUHB | KUHLMAN BROS INC | | | SCAC3 |
| 65 | KUHF | KUHN, LOWELL F | | | SCAC3 |
| 66 | KUHK | KUHN TRUCKING SERVICE | | | SCAC3 |
| 67 | KUHL | KUHL, ROLLIN H TRUCKING | | | SCAC4 |
| 68 | KUHQ | KUHNS MOVING & STORAGE INC | | | SCAC3 |
| 69 | KUHW | KUHN, HARRY W INC | | | SCAC3 |
| 70 | KUJA | KUJAK TRANSPORT INC | | | SCAC3 |
| 71 | KUJS | KUHOLSKI, J & SON | | | SCAC3 |
| 72 | KUK | Kudlik Aviation Inc. | Callsign: Kudlik, | CDN | AVCODES |
| 73 | KUK | Kaiserlich Österreich-Ungarische Marine/Imperial Austro-Hungarian Navy | | A | TRAFFIC |
| 74 | KUL | Aircompany Luk Aero | Callsign: Lukira, | KZ | AVCODES |
| 75 | KULM | KULLMAN EXPRESS INC | | | SCAC4 |
| 76 | KULS | KOUNALAKIS, MARKOS | | | SCAC3 |
| 77 | KUMA | Kumamoto Electric Railway | | J | TRAFFIC |
| 78 | KUMA | Kummler+Matter AG | | CH | VKM |
| 79 | KUMC | Kumamoto City Transportation | | J | TRAFFIC |
| 80 | KUMK | KUHN, MIKE TRUCKING | | | SCAC3 |
| 81 | KUMM | KUMMER TRANSPORT INC | | | SCAC3 |
| 82 | KUMN | KUMIAI NAVIGATION (PTE) LTD | | | SCAC4 |
| 83 | KUN | Kunság Volán | | H | TRAFFIC |
| 84 | KUND | KUNDEL, RAY | | | SCAC3 |
| 85 | KUND | KUNDERT, DAVID KEITH | | | SCAC4 |
| 86 | KUNI | University of Kansas | Real: KU, City: Lawrence | USA | TRAFFIC |
| 87 | KUNK | KUNKLE TRANSFER & STORAGE CO | | | SCAC3 |
| 88 | KUNL | KOC LLC | | | SCAC4 |
| 89 | KUNO | KUNOCO | | | SCAC4 |
| 90 | KUNQ | KUNYOUNG SHIPPING CO LTD. | | | SCAC3 |
| 91 | KUP | SkyUp Airlines | Callsign: Skyup, ICAO code changed to SQP w.e.f. 17 Augsut 2018. | UA | AVCODES |
| 92 | KUR | Kura Kura Aviation, PT. | Callsign: Kay-Aviation, Name changed to Whitesky Aviation Indonesia, PT. during 2010. | RI | AVCODES |
| 93 | KUR | Whitesky Aviation Indonesia | Callsign: Kay-Aviation, Name changed from Kura Kura Aviation, PT. during 2010. | RI | AVCODES |
| 94 | KUR | Kurobe Gorge Railway | | J | TRAFFIC |
| 95 | KUR | Christian Ruzika und Thomas Kaiser GbR | | DE | VKM |
| 96 | KURE | Kure City Transportation Bureau | | J | TRAFFIC |
| 97 | KURF | KURK FUEL CO | | | SCAC4 |
| 98 | KURI | KUPARI SHIPPING COMPANY LIMITED | | | SCAC3 |
| 99 | KURK | KURK, DAVID INC | | | SCAC3 |
| 100 | KURSKE | MUP Kurskelektrotrans | City: Kursk | RUS | TRAFFIC |
