| 6601 | SLZQ | S O S LOGISTICS INC | | | SCAC4 |
| 6602 | SLZS | SCOUT LOGISTICS CORPORATION | | | SCAC4 |
| 6603 | SLZT | SCHULZ TRANSPORTATION SERVICES INC | | | SCAC4 |
| 6604 | SLZU | CS LEASING PTE LTD | | SGP | BIC |
| 6605 | SLZU | CARU Specialized Leasing | | | RSRV |
| 6606 | SLZV | SOLIS, LUIS A TRUCKING | | | SCAC4 |
| 6607 | SM | Sunworld International Airlines, Inc. | ICAO: SWI, Callsign: Sunworld, IATA Prefix: 375, Designator SM recalled by IATA | USA | AVCODES |
| 6608 | SM | Peregrine Air Services Ltd. d/b/a Aberdeen Airways | ICAO: AAW, Subsidary of Air Provence | GB | AVCODES |
| 6609 | SM | Altair Linee Aeree S.p.A. | ICAO: SMI, Callsign: Sierra Mike, Ceased Operations | I | AVCODES |
| 6610 | SM | Air Ecosse Ltd | ICAO: ECS, Callsign: Ecosse Air, Founded in 1977 | GB | AVCODES |
| 6611 | SM | Southend Municipal Flying School | Callsign: Scofly, | GB | AVCODES |
| 6612 | SM | Swedline Express AB | ICAO: SRL, Callsign: Starline, IATA designator changed from T9*. Name changed from AB Varmlandsflyg w.e.f. 01 December 2002. | S | AVCODES |
| 6613 | SM | Spirit of Manila Airlines Corp | ICAO: MNP, Callsign: Manila Sky, IATA Prefix: 976, | RP | AVCODES |
| 6614 | SM | Air Cairo | ICAO: MSC, IATA Prefix: 381, IATA designator changed to SM. Founded in 2003 | ET | AVCODES |
| 6615 | SM | St. Marys R.R. Co. | 1/1975; eliminated 1/1979; 1/1980-7/2000; eliminated 7/2004; 7/2005 | | NAKINA |
| 6616 | SM | St. Marys R.R. Co. | 1/75; eliminated 1/79; 1/80-7/2000 | | NRHS |
| 6617 | SM | ST. MARYS RAILROAD CO. | | | PWRC |
| 6618 | SM | St. Mary's Railroad | | | RSRV |
| 6619 | SM | SAINT MARYS RAILROAD COMPANY | | | SCAC4 |
| 6620 | SM | St. Marys R.R. Co. | | USA | TRAFFIC |
| 6621 | SM | Scandinavian Motortransport AB | | SE | VKM |
| 6622 | SMA | SMA Airlines Nig. Limited | Callsign: Sesame, | WAN | AVCODES |
| 6623 | SMA | SMA Airlines | | | ICAO1 |
| 6624 | SMA | San Manuel Arizona R.R. Co. | 1/1975-7/2005 | | NAKINA |
| 6625 | SMA | San Manuel Arizona R.R. Co. | 1/75-7/2000 | | NRHS |
| 6626 | SMA | SAN MANUEL ARIZONA RAILROAD COMPANY | | | PWRC |
| 6627 | SMA | San Manuel Arizona Railroad | | | RSRV |
| 6628 | SMAA | SEA MASTER SHIPPING GMBH | | | SCAC4 |
| 6629 | SMAB | SMALL, BLAKE F | | | SCAC4 |
| 6630 | SMAC | STEELMASTE | | | SCAC4 |
| 6631 | SMAE | SAM EXPRESS | | | SCAC4 |
| 6632 | SMAG | STATE MARINE-ISTHMIAN AGENCY INC. | | | PWRC |
| 6633 | SMAH | SMITH FARM SERVICE INC | | | SCAC4 |
| 6634 | SMAL | SMITH, AL MOVING AND FURNITURE CO I | | | SCAC4 |
| 6635 | SMAM | STREETER, MATT L TRUCKING | | | SCAC4 |
| 6636 | SMAQ | S & M TRANSPORT INC | | | SCAC4 |
| 6637 | SMAR | STERLING MARINE TRANSPORT LLC | | | SCAC4 |
| 6638 | SMAR | South Maitland Railways | Real: SMR | AUS | TRAFFIC |
| 6639 | SMART | SMART CORPORATION s.r.o. | | SK | VKM |
| 6640 | SMARTC | Sonoma–Marin Area Rail Transit | Real: SMART | US-CA | TRAFFIC |
| 6641 | SMARTD | Suburban Mobility Authority for Regional Transportation | Real: SMART, City: Detroit, Beginning operations in 1967 as the Southeastern Michigan Transportation Authority (SEMTA) in Wayne, Oakland and Macomb Counties. Its name was changed to SMART in 1989. | USA | TRAFFIC |
| 6642 | SMAS | SOUND MOVING AND STORAGE (DIV OF JA | | | SCAC4 |
| 6643 | SMAU | SMART CONTAINERS KAMIL BIESZK | | PL | BIC |
| 6644 | SMAU | AUSIMONT S.P.A., MONTEDISON INTERMI | | | SCAC3 |
| 6645 | SMAU | AUSIMONT S.P.A., MONTEDISON INTERMI | | | SCAC4 |
| 6646 | SMAV | SUMMI | | | SCAC4 |
| 6647 | SMAX | Siemens-Allis, Inc. | added 4/1985; eliminated 4/1986 | | NAKINA |
| 6648 | SMAX | Siemens | added 4/1986; eliminated 10/1988 | | NAKINA |
| 6649 | SMAX | Siemens-Allis, Inc. | added 4/85; eliminated 4/86 | | NRHS |
| 6650 | SMAX | Siemens | added 4/86; eliminated 10/88 | | NRHS |
| 6651 | SMAX | SIEMENS INC. [SIEMENS-ALLIS, INC.] | | | PWRC |
| 6652 | SMB | Simba Air Cargo Ltd. | Callsign: Simbair, Ceased operations. | EAK | AVCODES |
| 6653 | SMB | Solothurn - Moutier-Bahn | | CH | TRAFFIC |
| 6654 | SMBC | SIMBEL E N E | | | SCAC4 |
| 6655 | SMBF | SMITH, JOHN D TRUCKING LLC | | | SCAC4 |
| 6656 | SMBI | SMB MFG INC | | | SCAC4 |
| 6657 | SMBJ | SMS TRUCKING INC | | | SCAC4 |
| 6658 | SMBK | SIMBECK INC | | | SCAC4 |
| 6659 | SMBL | SMITH BROTHERS TRANSPORT LLC | | | SCAC4 |
| 6660 | SMBN | SMITH TRUCKING INC | | | SCAC4 |
| 6661 | SMBO | SMITH BROTHERS TRUCKING CO INC | | | SCAC4 |
| 6662 | SMBP | SMOOT BROS TRANSPORTATION | | | SCAC4 |
| 6663 | SMBQ | SPECIALITES MB INC | | | SCAC4 |
| 6664 | SMBR | SMT TRUCKING COMPANY | | | SCAC4 |
| 6665 | SMBT | SERRATOS MOBILE HOMES | | | SCAC4 |
| 6666 | SMBU | SAMBU LINE, S.A. | | | SCAC4 |
| 6667 | SMBV | SOUTHERN MAINE SITEWORK INC | | | SCAC4 |
| 6668 | SMBW | SHARP, MICHAEL A TRUCKING | | | SCAC4 |
| 6669 | SMBY | SUPERS | | | SCAC4 |
| 6670 | SMC | Sabang Merauke Raya Air Charter PT. | Callsign: Samer, Name changed to SMAC (Sabang Merauke Raya Air Charter), PT. | RI | AVCODES |
| 6671 | SMC | SMAC (Sabang Merauke Raya Air Charter), PT. | Callsign: Samer, Name changed from Sabang Merauke Raya Air Charter PT. | RI | AVCODES |
| 6672 | SMC | Comlux San Marino S.r.l. | Callsign: Comlux, | RSM | AVCODES |
| 6673 | SMC | Sabang Merauke Raya Air Charter | | | ICAO1 |
| 6674 | SMC | A. E. STALEY MANUFACTURING CO. | | | PWRC |
| 6675 | SMC | Chemin de Fer & Autobus Sierre-Montana-Crans | | CH | TRAFFIC |
| 6676 | SMCD | SEAMATES CONSOLIDATION SERVICE INC | | | SCAC4 |
| 6677 | SMCE | SKYLINE MAIL CARRIERS INC | | | SCAC4 |
| 6678 | SMCF | SMITH CARTAGE INC | | | SCAC4 |
| 6679 | SMCF | Sercice Militaire des Chemines de Fer | | FR | VKM |
| 6680 | SMCI | SPECIAL MACHINING CO INC | | | SCAC4 |
| 6681 | SMCJ | SUMMERFORD TRUCK LINE INC | | | SCAC4 |
| 6682 | SMCL | SMITH, C. L., TRUCKING | | | SCAC1 |
| 6683 | SMCN | SAMS TRUCKING | | | SCAC4 |
| 6684 | SMCO | SAN MARCOS TRANSFER | | | SCAC4 |
| 6685 | SMCO | S.M.Coaches | | GB | TRAFFIC |
| 6686 | SMCP | SECO MANUFACTURING COMPANY INC | | | SCAC4 |
| 6687 | SMCQ | SMITH, W., CARTAGE COMPANY, INC | | | SCAC1 |
| 6688 | SMCQ | SMITH, W CARTAGE COMPANY INC | | | SCAC4 |
| 6689 | SMCT | SMITH, C R TRUCKING | | | SCAC4 |
| 6690 | SMCU | SM CONTAINER LINES | | ROK | BIC |
| 6691 | SMCU | ASTRIUM GMBH | | | SCAC4 |
| 6692 | SMCV | SAN MARCOS GROUP LLC | | | SCAC4 |
| 6693 | SMCX | Staso Milling Co. | 7/1930-7/1932 | | NAKINA |
| 6694 | SMCX | The Simmons Co. | 1/1943-1/1946 | | NAKINA |
| 6695 | SMCX | The Altus Co. | added 1/1962; eliminated 1/1963 | | NAKINA |
| 6696 | SMCX | Standard Milling Co. | added 1/1963; 7/1965-4/1970; eliminated 4/1972 | | NAKINA |
| 6697 | SMCX | San Miguel Electric Cooperative, Inc. | added 10/1981; 1/1994-7/2005 | | NAKINA |
| 6698 | SMCX | The Altus Co. | added 1/62 | | NRHS |
| 6699 | SMCX | Standard Milling Co. | 7/65-4/70; eliminated 4/72 | | NRHS |
| 6700 | SMCX | San Miguel Electric Cooperative, Inc. | added 10/81; 1/94-7/2000 | | NRHS |
