| KAC | KU | 229 | Kuwait Airways |
| KAH | Kent Aviation Services | ||
| KAJ | 5R | Karthago Airlines | |
| KAL | KE | 180 | Korean Air |
| KAO | KAPO - Kazan Aviation | ||
| KAP | 9K | 306 | Cape Air |
| KAV | 7F | 206 | Air Kufra |
| KAZ | Tatarstan Airlines | ||
| KDA | KD | 678 | Kendell Airlines |
| KDC | XC | KD Air Corporation | |
| KEA | Kalahari Express | ||
| KET | DZ | CAT Cargo Air Transport | |
| KFA | Kelowna Flightcraft Air Charter | ||
| KFR | IT | 090 | Kingfisher Airlines |
| KGA | K2 | 758 | Kyrgyzstan Airlines |
| KGL | Kogalymavia | ||
| KHA | KR | 798 | Kitty Hawk Aircargo |
| KHB | H8 | 560 | Dalavia |
| KHO | X9 | 852 | Khors Aircompany |
| KHR | Khazar Airline | ||
| KHY | Khyber Afghan Airlines | ||
| KIA | KP | 538 | Kiwi International Airlines |
| KIC | KC | 573 | Adagold Aviation |
| KIL | GW | 113 | Kuban Airlines |
| KIO | Krai Aero Russian Austrian | ||
| KIS | Contact Air | ||
| KJA | Avistar | ||
| KJC | 7B | 499 | KrasAir |
| KKB | WV | 399 | Air South Airlines |
| KKK | KK | 610 | Atlasjet |
| KLA | TT | 843 | Air Lithuania |
| KLC | KL | KLM City Hopper | |
| KLD | Air Klapeida | ||
| KLE | RusAero | ||
| KLI | Kolyma Avia Enterprise | ||
| KLM | KL | 074 | KLM Cargo |
| KLN | K8 | 097 | Kalingrad Air Enterprise |
| KLV | Key Avia | ||
| KMA | Komiavia Air Enterprise | ||
| KMG | Kosmas Air | ||
| KMP | E2 | 837 | Kampuchea Airlines |
| KMR | RQ | Kam Air | |
| KMZ | KR | Comores Aviation | |
| KNM | Komsomolsk na Amure | ||
| KNX | Knighthawk Air Express | ||
| KOR | JS | 120 | Air Koryo |
| KOS | Kosova Airlines | ||
| KPH | Kazan Plant of Helicopters | ||
| KQA | KQ | 706 | Kenya Airways |
| KRE | Aerosucre | ||
| KRI | Krilo Aviacompany Ltd | ||
| KRO | Kroonk Air Agency | ||
| KRP | V3 | 021 | Carpatair |
| KRS | 6K | 557 | Korsar Airlines |
| KRT | 0K | Kokshetau Airline | |
| KSA | KS Avia | ||
| KSM | Kosmos Airlines | ||
| KUS | Kursk State Air Enterprise | ||
| KWZ | K6 | Khalifa Airways | |
| KYC | Av Atlantic | ||
| KZA | K4 | 736 | Kazakhstan Airlines (Kazair) |
| KZK | 9Y | 452 | Air Kazakhstan |
| KZR | 4L | 465 | Air Astana |
| KZU | GO | 444 | Kuzu Airlines Cargo |