| 1 | RK | Air Afrique | ICAO: RKA, Callsign: Airafric, IATA Prefix: 092, Declared bankrupt on 07 February 2002. | CI | AVCODES |
| 2 | RK | Royal Khmer Airlines | ICAO: RKH, Callsign: Khmer Air, Designator RK reinstated by IATA. Designator FE recalled by IATA | K | AVCODES |
| 3 | RK | Region-Airline | Founded in 2005. Commenced operations in 2006, Ceased operations in 2011. | RUS | AVCODES |
| 4 | RK | Skyview Airways Co., Ltd. d/b/a Skyview | ICAO: RCT, Callsign: Green Sky, Founded in 2012. | T | AVCODES |
| 5 | RK | Ryanair UK Limited | ICAO: RUK, Callsign: Blue Max, | GB | AVCODES |
| 6 | RK | Rhenus Keolis GmbH & Co. KG | Mainz | D | privat-bahn.de |
| 7 | RK | Rendsburger Kreisbahn | | D | TRAFFIC |
| 8 | RK | Rhenus Keolis GmbH | | DE | VKM |
| 9 | RKA | Air Afrique | IATA: RK, Callsign: Airafric, IATA Prefix: 092, Declared bankrupt on 07 February 2002. | CI | AVCODES |
| 10 | RKA | Polar Airlines, State Unitary Enterprise Air Company | Callsign: Air Sakha, Name changed to Polar Airlines OJSC | RUS | AVCODES |
| 11 | RKA | Polar Airlines OJSC | IATA: PI, Callsign: Air Sakha, Name changed from Polar Airlines, , State Unitary Enterprise Air Company. Purchased by JSC Airline Yakutia (R3/SYL) | RUS | AVCODES |
| 12 | RKA | Air Afrique | | | ICAO1 |
| 13 | RKAB | RENKAS, CRAIG W | | | SCAC4 |
| 14 | RKAL | RECKART LOGISTICS INC. | | | SCAC4 |
| 15 | RKAM | R & KA | | | SCAC4 |
| 16 | RKAP | RED KAP SALES INC | | | SCAC4 |
| 17 | RKB | Rødkærsbro - Kjellerup Banen (Kjellerupbanen) | 1912 - 1924 | DK | jernbanen.dk |
| 18 | RKB | Rødkærsbro - Kjellerup Banen (Kjellerupbanen) | 1912 - 1924 | DK | TRAFFIC |
| 19 | RKBF | ROCKY BEACH FARMS INC | | | SCAC3 |
| 20 | RKBL | ROYAL KENT BUS LINES INC | | | SCAC3 |
| 21 | RKBL | RAKEBY LIMITED | | | SCAC4 |
| 22 | RKBQ | RIVERA, K & B LIQUID LOGISTICS LLC | | | SCAC4 |
| 23 | RKBS | RICKS BACKHOE SERVICE INC | | | SCAC4 |
| 24 | RKC | Das Airlines | Callsign: Das Congo, | ZRE | AVCODES |
| 25 | RKC | DAS Airlines | | | ICAO1 |
| 26 | RKCC | ROCKET CITY CHARTER SERVICE INC | | | SCAC3 |
| 27 | RKCE | ROCK CREEK EXPRESS INC | | | SCAC3 |
| 28 | RKCG | RUKY INTERNATIONAL COMPANY | | | SCAC4 |
| 29 | RKCL | RIMROCK COLONY | | | SCAC4 |
| 30 | RKCT | ROCK CREEK TRUCKING | | | SCAC4 |
| 31 | RKCW | RAKOWSKI CARTAGE & WRECKING LTD | | | SCAC4 |
| 32 | RKCX | Knox Kershaw, Inc. | added 1/1984; eliminated 4/1985; 1/1994-7/2005 (not listed) | | NAKINA |
| 33 | RKCX | Royce Kershaw Co., Inc. | eliminated 1/1984 | | NAKINA |
| 34 | RKCX | Knox Kershaw Co., Inc. | added 1/1969; 4/1970-1/1980 | | NAKINA |
| 35 | RKCX | Knox Kershaw Co., Inc. | added 1/69; 4/70-1/80; eliminated 4/85; 1/94-7/2000 | | NRHS |
| 36 | RKCX | *KNOX KERSHAW INC (ROYCE KERSHAW CO., INC.) | | | PWRC |
| 37 | RKCX | Knox Kershaw | | | RSRV |
| 38 | RKCX | KNOX KERSHAW INC | | | SCAC4 |
| 39 | RKCY | RANDOLPH PACKING CO | | | SCAC4 |
| 40 | RKDA | ROCKDALE TRANSPORTATION ENTERPRISES | | | SCAC4 |
| 41 | RKDB | ROCK LEASING INC | | | SCAC4 |
| 42 | RKDC | ROCKSIDE DISTRIBUTION CENTER | | | SCAC3 |
| 43 | RKDC | ROADSTAR TRUCKING INC | | | SCAC4 |
| 44 | RKDF | R K D FARMS | | | SCAC3 |
| 45 | RKDF | RINKER BOAT COMPANY LLC | | | SCAC4 |
| 46 | RKDG | R K D TRUCKING INC | | | SCAC3 |
| 47 | RKDG | ROGERS TRUCKS & EQUIPMENT INC | | | SCAC4 |
| 48 | RKDI | ROCKETT DELIVERY SERVICE | | | SCAC3 |
| 49 | RKDL | RINKER, DALE F | | | SCAC3 |
| 50 | RKEB | RIDDICK ENTERPRISES INC | | | SCAC4 |
| 51 | RKED | ROAD KING ENTERPRISES AND DISTRIBUT | | | SCAC4 |
| 52 | RKEE | R & K EXPRESS INC | | | SCAC4 |
| 53 | RKEF | ROAD KING EXPRESS FREIGHT INC | | | SCAC4 |
| 54 | RKEI | ROCKET EXPRESS INC | | | SCAC3 |
| 55 | RKEN | ROCKET TRANSPORTATION INC | | | SCAC3 |
| 56 | RKEN | RYKER ENTERPRISES INC | | | SCAC4 |
| 57 | RKEP | ROCKET EXPRESS | | | SCAC3 |
| 58 | RKEQ | ROCKEY, M F MOVING COMPANY | | | SCAC3 |
| 59 | RKEQ | ROCKY BAR RANCH | | | SCAC4 |
| 60 | RKER | R K DISTRIBUTING INC | | | SCAC4 |
| 61 | RKES | ROCKET EXPRESS INC | | | SCAC3 |
| 62 | RKES | ROCKIN K ENTERPRISES LLC | | | SCAC4 |
| 63 | RKET | ROCKET TRUCKING | | | SCAC3 |
| 64 | RKEV | RACE KIT EVENT SERVICE INC | | | SCAC4 |
| 65 | RKEY | ROCKFORD, KERRY ENTERPRISES INC | | | SCAC4 |
| 66 | RKFC | ROCKFORD CARRIER INC | | | SCAC4 |
| 67 | RKFI | R K FUELS INC | | | SCAC4 |
| 68 | RKFL | ROCK FALLS FREIGHT & LEASING CORP | | | SCAC3 |
| 69 | RKFM | REMARK FRESH MARKETS | | | SCAC4 |
| 70 | RKFT | RKF TRUCK LINES LTD | | | SCAC3 |
| 71 | RKG | Rockingham R.R. (Co.) | 7/1923-10/1966 | | NAKINA |
| 72 | RKG | Rockingham R.R. Co. | 4/38-10/66 | | NRHS |
| 73 | RKG | ROCKINGHAM RAILROAD CO. | | | PWRC |
| 74 | RKGI | R & K LOGISTICS INC | | | SCAC4 |
| 75 | RKGL | RICE TRUCKING LLC | | | SCAC4 |
| 76 | RKGN | RESOURCES TRUCKING OF CALIFORNIA IN | | | SCAC3 |
| 77 | RKGP | ROCKING R TRANSPORT | | | SCAC4 |
| 78 | RKGQ | RKG CARRIERS INC | | | SCAC4 |
| 79 | RKGT | ROCKING T INC | | | SCAC4 |
| 80 | RKGX | River King Coal | | | RSRV |
| 81 | RKH | Royal Khymer Airlines | IATA: FE, Callsign: Khymer Air, Designator FE recalled by IATA | K | AVCODES |
| 82 | RKH | Royal Khmer Airlines | IATA: RK, Callsign: Khmer Air, Designator RK reinstated by IATA. Designator FE recalled by IATA | K | AVCODES |
| 83 | RKH | Royal Khmer Airlines | IATA: RK | | ICAO1 |
| 84 | RKH | Regionalverkehr Kurhessen GmbH | | D | TRAFFIC |
| 85 | RKHA | ROCK HAULERS INC | | | SCAC3 |
| 86 | RKHA | ROCKET DELIVERY INC | | | SCAC4 |
| 87 | RKHD | RKH INDUSTRIES INC | | | SCAC4 |
| 88 | RKHI | RICH TRUCKING INC | | | SCAC4 |
| 89 | RKHJ | ROCKHILL, H J INC | | | SCAC3 |
| 90 | RKHU | RIN KAGAKU KOGYO CO LTD | | J | BIC |
| 91 | RKIA | ROCK-IT CARGO USA LLC | | | SCAC4 |
| 92 | RKIB | ROCK-IT CARGO USA LLC | | | SCAC4 |
| 93 | RKIC | ROCK-IT CARGO USA INC | | | SCAC3 |
| 94 | RKIC | ROCK-IT CARGO USA LLC | | | SCAC4 |
| 95 | RKIG | ROYAL KING ENTERPRISE LTD | | | SCAC4 |
| 96 | RKIK | RKI | | | SCAC4 |
| 97 | RKIP | ROCK IMPLEMENT INC | | | SCAC3 |
| 98 | RKIT | RANKIN TRUCKING, INC | | | SCAC3 |
| 99 | RKIW | ROCK-IT CARGO USA LLC | | | SCAC4 |
| 100 | RKK | Stephens Investment Holdings, LLC | Callsign: Rocktown, | USA | AVCODES |
