| 1 | SK | Scandinavian Airlines System (SAS) | ICAO: SAS, Callsign: Scandinavian, IATA Prefix: 117, | S | AVCODES |
| 2 | SK | Snowflake | ICAO: SAS, Commenced operations on 19 March 2003. Merged back into SAS 31 October 2004. Low cost business unit of SAS Scandinavian Airlines (SAS Group) | S | AVCODES |
| 3 | SK | Siegener Kreisbahn GmbH | Siegen | D | privat-bahn.de |
| 4 | SK | Seehafen Kiel GmbH & Co KG | Kiel | D | privat-bahn.de |
| 5 | SK | Siegener Kreisbahn | Renamed to KSW - Kreisbahn Siegen-Wittgenstein GmbH | D | TRAFFIC |
| 6 | SKA | Rio Air Express S/A | Callsign: Rio Express, | BR | AVCODES |
| 7 | SKA | Skyjet Brasil | Callsign: Rio Express, | BR | AVCODES |
| 8 | SKA | Skegness Air Taxi Services Ltd. d/b/a Skegair | Callsign: Skegair, | GB | AVCODES |
| 9 | SKA | Rio Air Express | | | ICAO1 |
| 10 | SKAD | SKATEBOARD EXPRESS | | | SCAC4 |
| 11 | SKAE | SCHULTZ, KELLY ANTIQUES | | | SCAC4 |
| 12 | SKAF | Slovak Air Force | | SK | TRAFFIC |
| 13 | SKAG | SKAGIT FARMERS SUPPLY | | | SCAC4 |
| 14 | SKAI | SKAR TRUCKING INC | | | SCAC4 |
| 15 | SKAJ | Stockholms Kultursällskap för Ånga och Järnväg | | SE | VKM |
| 16 | SKAM | SEAHAW | | | SCAC4 |
| 17 | SKAN | SPRINGFIELD TRUCK LINE LLC | | | SCAC4 |
| 18 | SKAND | SKAND Skalica | | SK | TRAFFIC |
| 19 | SKANE | Skanetrafiken | | S | TRAFFIC |
| 20 | SKANE | Skånetrafiken | | SE | VKM |
| 21 | SKANS | Skanska a.s. | | CZ | VKM |
| 22 | SKAP | SKYLINE DECKING LTD | | | SCAC4 |
| 23 | SKAQ | SEA LINK TRANSPORT INC | | | SCAC4 |
| 24 | SKAR | SASKARC INDUSTRIES INC | | | SCAC4 |
| 25 | SKASK | Skanska SK a.s. | | SK | VKM |
| 26 | SKAT | SKAGIT TRANSPORTATION INC | | | SCAC4 |
| 27 | SKAU | SKAFF CRYOGENICS INC | | USA | BIC |
| 28 | SKAU | Skaff Cryogenics | | | RSRV |
| 29 | SKB | Skyfreighters Corp. | Callsign: Skybus, | USA | AVCODES |
| 30 | SKB | Skybus Airlines | IATA: SX, Callsign: Skybus, Ceased operations | USA | AVCODES |
| 31 | SKB | Skybus Airlines | IATA: SX | | ICAO1 |
| 32 | SKB | Schleifkottenbahn GmbH | Halver | D | privat-bahn.de |
| 33 | SKBA | SKIP BARBER RACING SCHOOL LLC | | | SCAC4 |
| 34 | SKBB | SKYLINE CUSTOMS SERVICES LLC | | | SCAC4 |
| 35 | SKBF | SNEAKER KING OF BUFFALO | | | SCAC4 |
| 36 | SKBN | SKIPPER BROTHERS TANK LINES LLC | | | SCAC4 |
| 37 | SKBO | SKEETER BROKERAGE | | | SCAC4 |
| 38 | SKBP | SMOKY BURN TRANSPORT | | | SCAC4 |
| 39 | SKBQ | STREET KINGS INC | | | SCAC4 |
| 40 | SKBR | SHOKER BROTHERS INCORPORATED | | | SCAC4 |
| 41 | SKBU | SWEDISH NUCLEAR FUEL AND WASTE MANAGEMENT | | S | BIC |
| 42 | SKBY | SKY-BLUE LOGISTICS LLC | | | SCAC4 |
| 43 | SKC | Skymaster Air Lines Ltda | Callsign: Skymaster Air, Established on 30 November 1995 and started operations in 1997. Ceased operations. | BR | AVCODES |
| 44 | SKC | Skymaster Air Lines | | | ICAO1 |
| 45 | SKCB | SENKO CO LTD | | | SCAC4 |
| 46 | SKCC | SCHECKLA, CRAIG LLC | | | SCAC4 |
| 47 | SKCE | STARLINK CONSOLIDATION SERVICE | | | SCAC4 |
| 48 | SKCF | SITKA COURIER LLC | | | SCAC4 |
| 49 | SKCG | STRICKLAND OIL CO INC | | | SCAC4 |
| 50 | SKCI | SKIERS CHOICE INC | | | SCAC4 |
| 51 | SKCJ | SKYTRUCK CONTAINER LINES | | | SCAC4 |
| 52 | SKCO | SRA KARTING INTERNATIONAL | | | SCAC4 |
| 53 | SKCQ | STICKY MEDIA INC | | | SCAC4 |
| 54 | SKCR | SKY COURIER NETWORK | | | SCAC4 |
| 55 | SKCU | MAMMOET EUROPE BV | | NL | BIC |
| 56 | SKCU | ALE HEAVYLIFT LIMITED | | | SCAC4 |
| 57 | SKCW | SOFILINK CONTINENTAL INC | | | SCAC4 |
| 58 | SKCX | Spartan Co-operative Creamery Co. (North Western Refrigerator Line Co.) | 7/1935 | | NAKINA |
| 59 | SKCX | Sinclair-Koppers Co. | added 1/1968; 4/1970; eliminated 1/1974 | | NAKINA |
| 60 | SKCX | Arco Polymers, Inc. | added 1/1974; eliminated 10/1974 | | NAKINA |
| 61 | SKCX | ARCO/Polymers, Inc. | added 10/1974; 1/1975; eliminated 10/1979 | | NAKINA |
| 62 | SKCX | ARCO Polymers, Inc. | added 10/1979; 1/1980; eliminated 10/1982 | | NAKINA |
| 63 | SKCX | ARCO Chemical Co. | added 10/1982; eliminated 1/1984; 1/1994-7/2005 (not listed) | | NAKINA |
| 64 | SKCX | Sinclair-Koppers Co. | added 1/68; 4/70 | | NRHS |
| 65 | SKCX | ARCO Polymers, Inc. | 1/75-1/80; eliminated 10/82 | | NRHS |
| 66 | SKCX | ARCO Chemical Co. | added 10/82; 1/94-7/2000 | | NRHS |
| 67 | SKCX | ARCO CHEMICAL CO. [SINCLAIR-KOPPERS CO.] | | | PWRC |
| 68 | SKCX | ARCO Chemical | | | RSRV |
| 69 | SKCY | SKY COUNTRY TRANSPORTATION SERVICES | | | SCAC4 |
| 70 | SKD | Sky Harbor Air Service, Inc. | Callsign: Sky Dwag, | USA | AVCODES |
| 71 | SKD | Skyguard Ltd. | Callsign: Skyguard, Ceased aviation business during 1990 | GB | AVCODES |
| 72 | SKD | Sky Harbor Air Service | | | ICAO1 |
| 73 | SKDA | SEMPER TRUCKING INC | | | SCAC4 |
| 74 | SKDB | SILKROAD LOGISTICS | | | SCAC4 |
| 75 | SKDE | SAN KARLOS S DE RL DE | | | SCAC4 |
| 76 | SKDF | STOCKARD ENTERPRISES INC | | | SCAC4 |
| 77 | SKDP | STRICKLAND & SONS PIPELINE INC | | | SCAC4 |
| 78 | SKDQ | SOKIL TRUCKING INC | | | SCAC4 |
| 79 | SKDR | SKANDACOR DIRECT INC | | | SCAC4 |
| 80 | SKDT | STRUCTURES DEREK INTERNATIONAL S A | | | SCAC4 |
| 81 | SKDY | SERHIENKO, DENNIS | | | SCAC4 |
| 82 | SKE | Sky Tours, Inc. | Callsign: Skyisle, | USA | AVCODES |
| 83 | SKE | Sky Tours | | | ICAO1 |
| 84 | SKEA | SKY BROKERAGE | | | SCAC4 |
| 85 | SKEC | STOKELY CREEK CARRIERS | | | SCAC4 |
| 86 | SKEF | STARKE ENTERPRISES LLC | | | SCAC4 |
| 87 | SKEG | SHEPARD AND KEMNA ENGINEERED TRANSP | | | SCAC4 |
| 88 | SKEI | SHEIK HALAL FARMS INC | | | SCAC4 |
| 89 | SKEI | Shin-Keisei Electric Railway | | J | TRAFFIC |
| 90 | SKEJ | SAMEK ENTERPRISE LLC | | | SCAC4 |
| 91 | SKEK | SKELTON TRUCKING LLC | | | SCAC4 |
| 92 | SKEL | SIEDAK ENTERPRISES LLC | | | SCAC4 |
| 93 | SKEM | SKEEM | | | SCAC4 |
| 94 | SKEO | SKEE, K FUEL OIL | | | SCAC4 |
| 95 | SKEP | SUPERIOR BROKERAGE SERVICES INC | | | SCAC4 |
| 96 | SKEQ | SK TRANSPORT | | | SCAC4 |
| 97 | SKER | SPECK ENTERPRISE TRANSPORTATION INC | | | SCAC4 |
| 98 | SKES | SKE ENTERPRISES LTD | | | SCAC4 |
| 99 | SKEV | SOLIE, KEVIN | | | SCAC4 |
| 100 | SKEW | STEELMAN, | | | SCAC4 |
