| 4801 | SICR | SCHAKE INDUSTRIES INC | | | SCAC4 |
| 4802 | SICT | SV TRUCKING SERVICES LLC | | | SCAC4 |
| 4803 | SICU | SHANGHAI XURONG CONTAINERCO., LTD | | PRC | BIC |
| 4804 | SICU | SIC PROCESSING GMBH | | | SCAC4 |
| 4805 | SICW | SICOMSA | | | SCAC4 |
| 4806 | SICX | Sloss Industries Corp. | added 7/1988; 1/1994-7/2000; eliminated 1/2005; 7/2005 (not listed) | | NAKINA |
| 4807 | SICX | Sloss Industries Corp. | added 7/88; 1/94-7/2000 | | NRHS |
| 4808 | SICX | SLOSS INDUSTRIES CORPORATION | | | PWRC |
| 4809 | SICX | Sloss Industries Corporation | | | RSRV |
| 4810 | SICX | SLOSS INDUSTRIES CORPORATION | | | SCAC4 |
| 4811 | SID | Sidfin Air Limited | Callsign: Sidfin, | Z | AVCODES |
| 4812 | SID | Sideral Linhas Aereas Ltda | Callsign: Sideral, | BR | AVCODES |
| 4813 | SIDB | SIDHU BROTHERS INC | | | SCAC4 |
| 4814 | SIDC | SIMONSEN TRUCKING | | | SCAC4 |
| 4815 | SIDE | SCHEIDERER TRANSPORT INC | | | SCAC4 |
| 4816 | SIDER | Siderpotenza Steel Works | | I | TRAFFIC |
| 4817 | SIDG | SIEDHOFF DISTRIBUTING CO | | | SCAC4 |
| 4818 | SIDH | SIDHU SERVICES LTD | | | SCAC4 |
| 4819 | SIDI | SHANE TRANSPORT, Shane Industries, INC | | | SCAC1 |
| 4820 | SIDI | SHANE TRANSPORT | | | SCAC4 |
| 4821 | SIDM | SINDALL TRANSPORT INC | | | SCAC4 |
| 4822 | SIDO | SERVICIOS INTEGRALES DE TRANSPORTES | | | SCAC4 |
| 4823 | SIDQ | STAR INDUSTRIES LLC | | | SCAC4 |
| 4824 | SIDS | SUPERIOR INTERMODAL SERVICES INC | | | SCAC4 |
| 4825 | SIDU | CHEMIKALIEN UND FLUESSIGKEITSTRANSPORTE A. SIEPMANN GMBH | | D | BIC |
| 4826 | SIDY | SINANO SHIPMANAGEMENT LIMITED | | | SCAC4 |
| 4827 | SIE | Sierra Express | Callsign: Serex, | USA | AVCODES |
| 4828 | SIE | Sierra Express | | | ICAO1 |
| 4829 | SIE | Siemens | | D | TRAFFIC |
| 4830 | SIEA | SIERRA AGRICULTURAL TRANSPORTATION | | | SCAC4 |
| 4831 | SIEB | SCHIELE ENTERPRISES INC | | | SCAC4 |
| 4832 | SIEB | | City: Siegburg | D | TRAFFIC |
| 4833 | SIEC | STRIVE TRANSPORT GROUP LLC | | | SCAC4 |
| 4834 | SIED | Miejskie Przedsiębiorstwo Komunikacyjne w Siedlcach Spółka z o.o. | | PL | TRAFFIC |
| 4835 | SIEE | SAIL GMBH | | | SCAC4 |
| 4836 | SIEG | | City: Siegen | D | TRAFFIC |
| 4837 | SIEH | SPIECH FARMS | | | SCAC4 |
| 4838 | SIEJ | SCHIERLMAN TRUCKING | | | SCAC4 |
| 4839 | SIEN | SIECOR | | | PWRC |
| 4840 | SIEP | SIRACUSA MOVING & STORAGE COMPANY I | | | SCAC4 |
| 4841 | SIEQ | SPEIGEL P T CO | | | SCAC4 |
| 4842 | SIER | SIERRA TRANSPORT LLC | | | SCAC4 |
| 4843 | SIER | Miejskie Przedsiębiorstwo Komunikacji w Sieradzu | Real: MPK, City: Sieradz | PL | TRAFFIC |
| 4844 | SIES | SIDEE ENTERPRISES INCORPORATED | | | SCAC4 |
| 4845 | SIESS | Siess Brennstoffe GmbH & Co KG | | AT | VKM |
| 4846 | SIET | SERVICIO INTERNACIONAL DE ENLACE TE | | | SCAC4 |
| 4847 | SIEU | SOMER S ISLE SHIPPING LTD | | BM | BIC |
| 4848 | SIEV | SIEVEKING INC | | | SCAC4 |
| 4849 | SIEX | Southern Iron & Equipment Co. | added 10/1970; eliminated 7/1972 | | NAKINA |
| 4850 | SIEX | Southern Iron & Equipment Co., Division U.S. Railway Manufacturing Co. | added 7/1972; 1/1975; eliminated 7/1977 | | NAKINA |
| 4851 | SIEX | Southern Iron & Equipment Co., Division Evans Transportation Co. | added 7/1977; eliminated 7/1979 | | NAKINA |
| 4852 | SIEX | United States Leasing Co. | added 7/1979; 1/1980 | | NAKINA |
| 4853 | SIEX | United States Railway Leasing Co. | eliminated 10/1980 | | NAKINA |
| 4854 | SIEX | Southeastern Industrial Enterprises, Inc. | added 4/1995; 7/2000-7/2005; eliminated 10/2006 | | NAKINA |
| 4855 | SIEX | Southern Iron & Equipment Co. | added 10/70 | | NRHS |
| 4856 | SIEX | Southern Iron & Equipment Co., Division U.S. Railway Manufacturing Co. | 1/75; eliminated 7/77 | | NRHS |
| 4857 | SIEX | Southern Iron & Equipment Co., Division Evans Transportation Co. | added 7/77; eliminated 7/79 | | NRHS |
| 4858 | SIEX | United States Leasing Co. | added 7/79; 1/80 | | NRHS |
| 4859 | SIEX | United States Railway Leasing Co. | eliminated 10/80 | | NRHS |
| 4860 | SIEX | Southeastern Industrial Enterprises, Inc. | added 4/95; 7/2000 | | NRHS |
| 4861 | SIEX | *UNITED STATES RAILWAY LEASING CO. [SOUTHERN IRON & EQUIPMENT CO.} | | | PWRC |
| 4862 | SIEX | +SOUTHEASTERN INDUSTRIAL ENTERPRISES | | | PWRC |
| 4863 | SIEX | Southeastern Industrial Enterprises | | | RSRV |
| 4864 | SIEX | SOUTHEASTERN INDUSTRIAL ENTERPRISES | | | SCAC4 |
| 4865 | SIEY | SIERRA SPECIALISED TRANSPORT | | | SCAC4 |
| 4866 | SIF | Skycy Freighters International Ltd. | Callsign: Skycy, | EAK | AVCODES |
| 4867 | SIF | AirSial Limited | IATA: PF, Callsign: Air Sial, | PK | AVCODES |
| 4868 | SIFA | SIFANDROS CARRIER LTD | | | SCAC4 |
| 4869 | SIFD | SIRIUS INTERNATIONAL FREIGHT FORWAR | | | SCAC4 |
| 4870 | SIFE | SUPERIOR INTERNATIONAL FREIGHT FORW | | | SCAC4 |
| 4871 | SIFF | SCHENKER INC | | | SCAC4 |
| 4872 | SIFI | SILFIES, F T INC | | | SCAC4 |
| 4873 | SIFM | SIL LLC | | | SCAC4 |
| 4874 | SIFO | SIFNOS TANKER CORPORATION | | | SCAC4 |
| 4875 | SIFP | STEELTECH INDUSTRIAL FABRICATION IN | | | SCAC4 |
| 4876 | SIFQ | STAR ICE & FUEL INC | | | SCAC4 |
| 4877 | SIFS | SIMONSON FREIGHT SERVICE | | | SCAC1 |
| 4878 | SIFT | Societá Italiana Ferrovie e Tranvie | | I | TRAFFIC |
| 4879 | SIFU | NEWPORT EUROPE B.V. | | NL | BIC |
| 4880 | SIFX | SIEMENS FINANCIAL SERVICES | | | SCAC4 |
| 4881 | SIG | Signature Aircraft Charter | Callsign: Signature, | GB | AVCODES |
| 4882 | SIGB | SOLAI CARTAGE INC | | | SCAC4 |
| 4883 | SIGD | SISTEMAS INTEGRALES DE LOGISTICA | | | SCAC4 |
| 4884 | SIGE | SIORDIA, GUILLERMO EDUARDO | | | SCAC4 |
| 4885 | SIGF | SIGMA FREIGHT INC | | | SCAC4 |
| 4886 | SIGG | SIGGINS OIL COMPANY | | | SCAC4 |
| 4887 | SIGH | SIG LOGISTICS | | | SCAC4 |
| 4888 | SIGI | SPRINGS GLOBAL US INC | | | SCAC4 |
| 4889 | SIGM | SIGMA LOGISTICS INC | | | SCAC4 |
| 4890 | SIGMA | SIGMA Sp. z o.o. | | PL | TRAFFIC |
| 4891 | SIGO | SIGURDSON FARMS GIMLI LTD | | | SCAC4 |
| 4892 | SIGP | SIGNATURE PLASTICS LLC | | | SCAC4 |
| 4893 | SIGQ | SPIRIT STORAGE INC | | | SCAC4 |
| 4894 | SIGR | SIGNATURE TRUCK LINES INC | | | SCAC4 |
| 4895 | SIGT | SIGNOR TRUCKING INC | | | SCAC4 |
| 4896 | SIGU | SINOAGE INTERNATIONAL LIMITED | | HK | BIC |
| 4897 | SIGU | STERLING INTERNATIONAL MOVERS | | | SCAC4 |
| 4898 | SIGX | Signal Gasoline Co. | 7/1932 | | NAKINA |
| 4899 | SIGX | Southern Indiana Gas and Electric Co. | added 4/1979; 1/1980-7/2000; eliminated 7/2002; 7/2005 (not listed) | | NAKINA |
| 4900 | SIGX | Southern Indiana Gas and Electric Co. | added 4/79; 1/80-7/2000 | | NRHS |
