| 5701 | SKM | Fayetteville Flying Service And Scheduled Skyways System | Callsign: Skytem, | USA | AVCODES |
| 5702 | SKM | Fayetteville Flying Service and Scheduled Skyways | | | ICAO1 |
| 5703 | SKM | Szybka Kolej Miejska w Warszawie | City: Warszawa | PL | TRAFFIC |
| 5704 | SKMD | STRIKLER METALS & DEMOLITION | | | SCAC4 |
| 5705 | SKMG | SEA HAWK MARINE LOGISTICS LLC | | | SCAC4 |
| 5706 | SKMK | SK-MK INC | | | SCAC4 |
| 5707 | SKML | SK METAL INC | | | SCAC4 |
| 5708 | SKMN | STOCKMAN OIL TWO INC | | | SCAC4 |
| 5709 | SKMO | SKIDMORE TRANSPORTATION SERVICES IN | | | SCAC4 |
| 5710 | SKMP | SK MOTORSPORTS LLC | | | SCAC4 |
| 5711 | SKMQ | SKALESKI MOVING & STORAGE INC | | | SCAC4 |
| 5712 | SKMS | SKANA IMAGING SOLUTIONS INC | | | SCAC4 |
| 5713 | SKMT | PKP Fast Urban Railway in Tricity Sp. z o. o. | | PL | TRAFFIC |
| 5714 | SKMT | PKP Szybka Kolej Miejska w Trojmiescie Sp. Z o.o. | | PL | VKM |
| 5715 | SKMU | MUTTI SRO | | SK | BIC |
| 5716 | SKMV | SKIDMORE | | | SCAC4 |
| 5717 | SKMW | SINOKOR MERCHANT MARINE CO LTD | | | SCAC4 |
| 5718 | SKMWA | Szybka Kolej Miejska Sp. z o.o. | | PL | TRAFFIC |
| 5719 | SKMWA | Szybka Kolej Miejska Sp. z o.o. | | PL | VKM |
| 5720 | SKN | Skyline Aviation Services, Inc. | Callsign: Skyliner, | USA | AVCODES |
| 5721 | SKN | Skyline Aviation Services | | | ICAO1 |
| 5722 | SKNA | SMITH, KENNETH R | | | SCAC4 |
| 5723 | SKNE | SKENE TRANSFER & SUPPLY | | | SCAC4 |
| 5724 | SKNJ | SIMRUT TRUCKING INC | | | SCAC4 |
| 5725 | SKNK | SANDERS, KEN TRUCKING | | | SCAC4 |
| 5726 | SKNL | SHINYO KANNIKA LIMITED | | | SCAC4 |
| 5727 | SKNN | SKINNER TRUCKING, INC | | | SCAC1 |
| 5728 | SKNS | SKINNER TRANSPORTATION INC | | | SCAC4 |
| 5729 | SKNU | KUEHNE + NAGEL AS | | N | BIC |
| 5730 | SKNV | SUPERIOR TANK LINES NORTHWEST DIVIS | | | SCAC4 |
| 5731 | SKNX | The Saskatchewan Grain Car Corp. | added 1/1981; eliminated 7/1985; 1/1994-7/2005 (not listed) | | NAKINA |
| 5732 | SKNX | The Saskatchewan Grain Car Corp. | added 1/81; 1/94-7/2000 | | NRHS |
| 5733 | SKNX | SASKATCHEWAN GRAIN CAR CORPORATION | | | PWRC |
| 5734 | SKNX | Saskatchewan Grain Car Corporation | | | RSRV |
| 5735 | SKNX | SASKATCHE | | | SCAC4 |
| 5736 | SKNX | Saskatchewan Grain Car Corporation | | USA | TRAFFIC |
| 5737 | SKO | Scottish Airways Flyers Ltd. | Callsign: Skywork, | GB | AVCODES |
| 5738 | SKO | Scottish Airways Flyers | | | ICAO1 |
| 5739 | SKODA | | | CZ | TRAFFIC |
| 5740 | SKOG | S S SKIKOS TRUCKING INC | | | SCAC4 |
| 5741 | SKOI | STARK OIL | | | SCAC4 |
| 5742 | SKOJ | SHOOKS OIL BURNER SERVICE & FUEL OI | | | SCAC4 |
| 5743 | SKOL | South Kansas & Oklahoma R.R., Inc. | added 4/1992; 1/1994; eliminated 1/1997; added 7/1998; 7/2000; eliminated 1/2005; added 4/2005; 7/2005 | | NAKINA |
| 5744 | SKOL | South Kansas & Oklahoma R.R., Inc. | added 4/92; 1/94; eliminated 1/97; added 7/98; 7/2000 | | NRHS |
| 5745 | SKOL | SOUTH KANSAS & OKLAHOMA RAILROAD, INC. | | | PWRC |
| 5746 | SKOL | South Kansas and Oklahoma Railroad | | | RSRV |
| 5747 | SKOL | SOUTH KANSAS & OKLAHOMA RAILROAD IN | | | SCAC4 |
| 5748 | SKOL | South Kansas & Oklahoma R.R., Inc. | | USA | TRAFFIC |
| 5749 | SKOM | SASHIKO MARITIME S A | | | SCAC4 |
| 5750 | SKON | SKELTON TRUCK LINES LTD | | | SCAC4 |
| 5751 | SKOR | SITKO, JOHN TRUCKING INC | | | SCAC4 |
| 5752 | SKOTR | ŠKODA AUTO a.s. | | CZ | VKM |
| 5753 | SKOV | SAMKOV TRANSPORT INC | | | SCAC4 |
| 5754 | SKOY | SOUTHWEST KANSAS COOP SERVICE CO LL | | | SCAC4 |
| 5755 | SKP | Aero-North Aviation Services | Callsign: Skipper, | CDN | AVCODES |
| 5756 | SKP | Skytrans Regional Pty Ltd t/a Skytrans Airlines | IATA: Q6, Callsign: Skytrans, Designator Q6 reinstated by IATA | AUS | AVCODES |
| 5757 | SKP | Skytrans Regional Pty Ltd t/a Skytrans Airlines | IATA: QN, Callsign: Skytrans, Designator Q6 recalled by IATA | AUS | AVCODES |
| 5758 | SKP | Aero-North Aviation Services | | | ICAO1 |
| 5759 | SKPA | SKYPARTS AVIATION | | | SCAC4 |
| 5760 | SKPB | SHOCKAKHA | | | SCAC4 |
| 5761 | SKPD | SOHI K P TRUCKING LTD | | | SCAC4 |
| 5762 | SKPE | STOCKTON PETROLEUM COMPANY INCORPOR | | | SCAC4 |
| 5763 | SKPF | STARK PRODUCTS | | | SCAC4 |
| 5764 | SKPG | SHAMROCK PRODUCE & BROKERAGE CORP | | | SCAC4 |
| 5765 | SKPI | SOUTH KENTUCKY PETROLEUM INC | | | SCAC4 |
| 5766 | SKPK | SKOPELOS PRODUCT TANKER CORPORATION | | | SCAC4 |
| 5767 | SKPL | SKYPORT LINES INC | | | SCAC4 |
| 5768 | SKPL | Stowarzyszenie Kolejowych Przewozów Lokalnych | | PL | TRAFFIC |
| 5769 | SKPL | SKPL Cargo Sp. z o.o | | PL | VKM |
| 5770 | SKPO | SKIPS OIL CO | | | SCAC4 |
| 5771 | SKPOST | Slovenská posta | Real: SP | SK | TRAFFIC |
| 5772 | SKPQ | SAMSKIP HF KEYKJAVIK ICELAND | | | SCAC4 |
| 5773 | SKPR | Southern Kent & Pacific R.R. Co. | 1/1994-7/2005 | | NAKINA |
| 5774 | SKPR | Southern Kent & Pacific R.R. Co. | 1/94-7/2000 | | NRHS |
| 5775 | SKPR | SOUTHERN KENT & PACIFIC RR CO. | | | PWRC |
| 5776 | SKPR | Southern Kent and Pacific RR | | | RSRV |
| 5777 | SKPT | SKIPAT TRUCKING CO | | | SCAC4 |
| 5778 | SKPV | SUMMERS CREEK ENTERPRISES INC | | | SCAC4 |
| 5779 | SKPX | Wm. Schluderberg-T.J. Kurdle Co. | 7/1930-7/1935 | | NAKINA |
| 5780 | SKPX | The Saskatchewan Grain Car Corp. | added 1/1981; eliminated 7/1985, 1/1994-7/2005 (not listed) | | NAKINA |
| 5781 | SKPX | The Saskatchewan Grain Car Corp. | added 1/81; 1/94-7/2000 | | NRHS |
| 5782 | SKPX | *WM. SCHULDERBERG-T.J. KURDLE CO. | | | PWRC |
| 5783 | SKPX | +SASKATCHEWAN GRAIN CAR CORPORATION | | | PWRC |
| 5784 | SKPX | Saskatchewan Grain Car Corporation | | | RSRV |
| 5785 | SKPX | SASKATCHE | | | SCAC4 |
| 5786 | SKQ | Labcorp, Inc. | Callsign: Skylab, | USA | AVCODES |
| 5787 | SKQ | Labcorp | | | ICAO1 |
| 5788 | SKQD | SUGAHARA KISEN CO LTD | | | SCAC4 |
| 5789 | SKQI | SCHMIDT TRUCKING INC | | | SCAC4 |
| 5790 | SKQL | SKILS INCORPORATED | | | SCAC4 |
| 5791 | SKQT | SHAMROCK TANK LINES LLC | | | SCAC4 |
| 5792 | SKQY | SKYLINE OIL COMPANY | | | SCAC4 |
| 5793 | SKR | Shonkar | Callsign: Shonkar, | RUS | AVCODES |
| 5794 | SKR | Skyscapes Air Charters | Callsign: Skyscapes, | ZA | AVCODES |
| 5795 | SKR | Skyscapes Air Charters | | | ICAO1 |
| 5796 | SKR | Shigaraki Kogen Railway | | J | TRAFFIC |
| 5797 | SKRA | SCHRADER, KEN RACING INC | | | SCAC4 |
| 5798 | SKRC | S K TRANSPORT INC | | | SCAC4 |
| 5799 | SKRD | SPEEDWORK | | | SCAC4 |
| 5800 | SKRI | SKRETTING (EAST COAST) | | | SCAC4 |
