| 1 | SX | Aeroejecutivo S.A. de C.V. | ICAO: AJO, Callsign: Aeroexo, IATA Prefix: 456, Ceased operations. | MEX | AVCODES |
| 2 | SX | SkyWork SA | ICAO: SRK, Callsign: Skyfox, | CH | AVCODES |
| 3 | SX | Scottish Airways | | GB | AVCODES |
| 4 | SX | Skybus Airlines | ICAO: SKB, Callsign: Skybus, Ceased operations | USA | AVCODES |
| 5 | SX | Skywagon Corporation, Inc. | IATA Prefix: 906, | USA | AVCODES |
| 6 | SX | flyGTA, Inc. | ICAO: TOR, Callsign: Homerun, IATA Prefix: 013, | CDN | AVCODES |
| 7 | SXA | Southern Cross Aviation, Inc. | Callsign: Ferry, ICAO Callsign changed from Southern Cross. | USA | AVCODES |
| 8 | SXA | Southern Cross Aviation | | | ICAO1 |
| 9 | SXAL | SUMMIT TRANSPORT LLC | | | SCAC4 |
| 10 | SXAR | STAR MARINE INC | | | SCAC4 |
| 11 | SXAT | SEMEX ALLIANCE, THE | | | SCAC4 |
| 12 | SXAV | SOLA TRANSPORT AGENCY INC | | | SCAC4 |
| 13 | SXBC | SIXTEEN (16) BROTHERS CORP | | | SCAC4 |
| 14 | SXBE | SELTEX BROKERAGE | | | SCAC4 |
| 15 | SXC | Sky Exec Aviation Services | Callsign: Sky Exec, | WAN | AVCODES |
| 16 | SXC | Sky Exec Aviation Services | | | ICAO1 |
| 17 | SXCC | SIX TWO FIVE SIX FIVE SEVEN ONE (62 | | | SCAC4 |
| 18 | SXCL | SILVER STATE EXPRESS LOGISTICS INC | | | SCAC4 |
| 19 | SXCN | S P EXPRESS INC | | | SCAC4 |
| 20 | SXCP | SUN EXPRESS CORPORATION | | | SCAC4 |
| 21 | SXCR | SOUTHERN CARRIERS INC | | | SCAC4 |
| 22 | SXCU | SHEREX CHEMICAL COMPANY INC | | | SCAC4 |
| 23 | SXD | SunExpress Deutschland GmbH | IATA: XG, Callsign: Sunrise, Ceased operations on 26 June 2020. Joint venture of Lufthansa and Turkish Airlines. | D | AVCODES |
| 24 | SXDC | SCHNELL EXPRESS LLC | | | SCAC4 |
| 25 | SXDD | SEXTON, D & D INC | | | SCAC4 |
| 26 | SXDI | STREAM TRADING INC | | | SCAC4 |
| 27 | SXDP | S & H EXPRESS INC (DEDICATED DIVISI | | | SCAC4 |
| 28 | SXDS | STALLION EXPEDING SERVICES | | | SCAC4 |
| 29 | SXDT | SPEEDX LOGISTICS | | | SCAC4 |
| 30 | SXE | Southeast Express Airlines, Inc. | Callsign: Dogwood Express, | USA | AVCODES |
| 31 | SXE | Southeast Express Airlines | | | ICAO1 |
| 32 | SXEA | SANTANA EXPRESS | | | SCAC4 |
| 33 | SXEC | SOUTHERN EXPEDITING CO INC | | | SCAC4 |
| 34 | SXEF | SIX EIGHT TWO SIX FOUR THREE ONE (6 | | | SCAC4 |
| 35 | SXEL | S & S EXPRESS LLC | | | SCAC4 |
| 36 | SXEN | S&S EXPRESS, INC | | | SCAC1 |
| 37 | SXEN | S & S EXPRESS INC | | | SCAC4 |
| 38 | SXEP | SERVICE EXPRESS INC | | | SCAC4 |
| 39 | SXES | SUPER EXPRESS GONZALEZ | | | SCAC4 |
| 40 | SXF | Southern Cross Aviation Inc., LLC | Callsign: Southern Flight, | USA | AVCODES |
| 41 | SXFI | SIX FIVE TWO SEVEN EIGHT EIGHT FOUR | | | SCAC4 |
| 42 | SXFR | SPEEDEX FREIGHT | | | SCAC4 |
| 43 | SXFS | ST LUCIA EXPRESS FREIGHT SERVICES I | | | SCAC4 |
| 44 | SXFT | STX FREIGHT COMPANY | | | SCAC4 |
| 45 | SXFV | SIX FIVE FIVE TWO FOUR THREE NINE ( | | | SCAC4 |
| 46 | SXG | SunExpress Deutschland GmbH | Callsign: German Sun, | D | AVCODES |
| 47 | SXGC | SIX EIGHT SEVEN ONE ONE ZERO ONE (6 | | | SCAC4 |
| 48 | SXGI | STX LOGISTICS INC | | | SCAC4 |
| 49 | SXHN | SIX THREE NINE FOUR SEVEN TWO EIGHT | | | SCAC4 |
| 50 | SXHP | SCAL EXPRESS | | | SCAC4 |
| 51 | SXHS | STAR EXHAUST SYSTEMS | | | SCAC4 |
| 52 | SXI | Southern Cross International | Callsign: Southern Cross, | NL | AVCODES |
| 53 | SXIA | SEAWINGS EXPRESS INTERNATIONAL LTD | | | SCAC4 |
| 54 | SXIE | STARLAX INTERNATIONAL CO | | | SCAC4 |
| 55 | SXIQ | SMX INC | | | SCAC4 |
| 56 | SXIS | SELECTIVE EXPRESS INC | | | SCAC4 |
| 57 | SXIT | SHANDEX TRUCK INC | | | SCAC4 |
| 58 | SXJ | Shanxi Shenfei Jet Co. Ltd. | Callsign: Big Wing, | PRC | AVCODES |
| 59 | SXKL | STX TRUCK LLC | | | SCAC4 |
| 60 | SXKP | SCORPIO PANAMAX TANKER POOL LTD | | | SCAC4 |
| 61 | SXL | Air Salamis Ltd. | Callsign: Air Salamis, | CY | AVCODES |
| 62 | SXL | Cornerstone Aviation, LLC d/b/a Skyline Flight | Callsign: Sonic, | USA | AVCODES |
| 63 | SXLF | SEATTLE TRANSPORTATION LOGISTICS LL | | | SCAC4 |
| 64 | SXLI | SOLEX LOGISTICS INC | | | SCAC4 |
| 65 | SXLL | SOUTHERN XPRESS LLC | | | SCAC4 |
| 66 | SXLQ | SOUTHEAST TRANSPORTATION AND LOGIST | | | SCAC4 |
| 67 | SXLT | SELECT EXPRESS & LOGISTICS | | | SCAC4 |
| 68 | SXLU | SUN XPRESS CONTAINER LINE-PTE LTD | | | SCAC4 |
| 69 | SXM | Servicios Aereos Especializados Mexicanos, S.A. de C.V. | Callsign: Servimex, | MEX | AVCODES |
| 70 | SXM | St. Maarten Airways | Callsign: Saint Maarten, | MAF | AVCODES |
| 71 | SXM | Servicios Aereos Sepecializados Mexicanos | | | ICAO1 |
| 72 | SXMC | SIMOES IMPORTS LLC | | | SCAC4 |
| 73 | SXML | SMT | | | SCAC4 |
| 74 | SXMP | SAERTEX MULTICOM LP | | | SCAC4 |
| 75 | SXMR | SIX MILE RED ANGUS LTD | | | SCAC4 |
| 76 | SXN | Sal Luftverkehrs GmbH | Callsign: Saxon, Name changed from Sal Luftverkehrs GmbH, Flughafen Leipzig-Halle | D | AVCODES |
| 77 | SXN | Südwestflug | Subsidary of Hahn Air / Using Hahn Air's IATA code HR | D | AVCODES |
| 78 | SXN | SaxonAir Charter Ltd. | Callsign: Saxonair, Part of Klyne Aviation Limited. | GB | AVCODES |
| 79 | SXNA | SIX-NATIONS INC | | | SCAC4 |
| 80 | SXNE | SUPREME TRANSPORTATION SOLUTIONS LL | | | SCAC4 |
| 81 | SXNF | SPIRIT TRANSPORTATION INC | | | SCAC4 |
| 82 | SXNI | SANT TRANS INC | | | SCAC4 |
| 83 | SXNJ | STONE'S EXPRESS OF NEW JERSEY, INC | | | SCAC1 |
| 84 | SXNJ | SLIPSTREAM EXPEDITED SERVICES INC | | | SCAC4 |
| 85 | SXNP | STRAIT TRANSPORT LLC | | | SCAC4 |
| 86 | SXNS | SEATTLE TRANS LLC | | | SCAC4 |
| 87 | SXOI | SPIRIT TRANSPORT INC | | | SCAC4 |
| 88 | SXOL | SAS TRANSPORT LLC | | | SCAC4 |
| 89 | SXOU | STELLA EXPRESS (SINGAPORE) PTE LTD | | SGP | BIC |
| 90 | SXOU | STELLA EXPRESS (SINGAPORE) PTE LTD | | | SCAC4 |
| 91 | SXOW | SPEEDCON EXPRESS LLC | | | SCAC4 |
| 92 | SXP | Sky Express Sp. z o. o. | Callsign: Express Sky, Merged into SprintAir - SRN | PL | AVCODES |
| 93 | SXP | Sky Express | | | ICAO1 |
| 94 | SXPA | SMART TRANSPORT INC | | | SCAC4 |
| 95 | SXPD | SIMORE TAXI & PARCEL DELIVERY LTD | | | SCAC4 |
| 96 | SXPE | STAR EXPRESS INC | | | SCAC4 |
| 97 | SXPF | S & L EXPRESS TRANSPORT LLC | | | SCAC4 |
| 98 | SXPG | STX PAN OCEAN SINGAPORE PTE LTD | | | SCAC4 |
| 99 | SXPH | SHUTTLE EXPRESS INC | | | SCAC4 |
| 100 | SXPI | STRIPCO EXPRESS INC | | | SCAC4 |
