| 1 | SY | Sun Country Airlines | ICAO: SCX, Callsign: Sun Country, IATA Prefix: 337, Name changed to MN Airlines, LLC d/b/a Sun Country Airlines w.e.f. July 2011. | USA | AVCODES |
| 2 | SY | Skyways International | Callsign: Skyways, | GB | AVCODES |
| 3 | SY | Air Alsace | | F | AVCODES |
| 4 | SY | United Air Service | ICAO: UHP, Callsign: Sierra Yankee, Designator SY recalled by IATA | WAN | AVCODES |
| 5 | SY | MN Airlines, LLC d/b/a Sun Country Airlines | ICAO: SCX, Callsign: Sun Country, IATA Prefix: 337, Name changed from Sun Country Airlines w.e.f. July 2011. | USA | AVCODES |
| 6 | SY | Sun Country Inc d/b/a Sun Country Airlines | ICAO: SCX, Callsign: Sun Country, IATA Prefix: 337, Name changed from MN Airlines, LLC d/b/a Sun Country Airlines and previously from Sun Country Airlines w.e.f. July 2011. | USA | AVCODES |
| 7 | SY | Syntus B.V. | | NL | TRAFFIC |
| 8 | SYA | Skyways, S.A. | Callsign: Lineas Cardinal, | RA | AVCODES |
| 9 | SYA | Syphax Airlines | IATA: FS, Callsign: Syphax, IATA Prefix: 393, Ceased operations on 30 July 2015. Founded ijn 2011. Commenced operations on 21 April 2012. | TN | AVCODES |
| 10 | SYA | Syphax Airlines S A | IATA: Y3, Callsign: Syphax, | TN | AVCODES |
| 11 | SYA | Skyways | | | ICAO1 |
| 12 | SYAA | SOULEYMANE | | | SCAC4 |
| 13 | SYAAF | Syrian Arab Armed Forces (القوات المسلحة العربية السورية) | Real: SAAF | SYR | TRAFFIC |
| 14 | SYAC | STRICTLY AIR & CARGO | | | SCAC4 |
| 15 | SYAE | SYKES, DEAN | | | SCAC4 |
| 16 | SYAL | SAMYOUNG AMERICA INC | | | SCAC4 |
| 17 | SYAN | SYRA NAVIGATION LTD | | | SCAC4 |
| 18 | SYB | Tempelhof Express Airlines GmbH | IATA: FC, Designator FC recalled by IATA. Name changed from TAL Thuringia Airlines GmbH | D | AVCODES |
| 19 | SYB | Symbol Publicidad, S.A. | Callsign: Symbolair, | E | AVCODES |
| 20 | SYB | TAL Thuringia Airlines GmbH | IATA: FC, Name changed to Tempelhof Express Airlines GmbH | D | AVCODES |
| 21 | SYB | Tempelhof Express Airlines GmbH | Designator FC recalled by IATA. Name changed from TAL Thuringia Airlines GmbH | D | AVCODES |
| 22 | SYB | Skyservice Business Aviation Inc | Callsign: Skybiz, | CDN | AVCODES |
| 23 | SYBC | SUDDATH RELOCATION SYSTEMS OF FT LA | | | SCAC4 |
| 24 | SYBD | STANLEY TRUCKING INC (LIQUID BOX DI | | | SCAC4 |
| 25 | SYBG | SUNNY LEASING INC | | | SCAC4 |
| 26 | SYBO | SHELLEY, R H | | | SCAC4 |
| 27 | SYBP | SKY BLUE TRANSPORT LTD | | | SCAC4 |
| 28 | SYBR | SEYBERT TRANSPORTATION SERVICES INC | | | SCAC4 |
| 29 | SYBT | STRATEGIC LOGISTICS COMPANY LLC | | | SCAC4 |
| 30 | SYBU | JIANGSU XINYUE HI-TECH (GROUP) CO.,LTD | | PRC | BIC |
| 31 | SYC | Systec 2000, Inc. | Callsign: Systec, | USA | AVCODES |
| 32 | SYC | Systec 2000 | | | ICAO1 |
| 33 | SYC | (The) Sylvania Central Ry. Co. (Wrightsville & Tennille R.R. Co.) | 7/1923-7/1936 | | NAKINA |
| 34 | SYC | WRIGHTSVILLE & TENNILLE RAILROAD CO. [SYLVANIA CENTRAL RWY. CO.] | | | PWRC |
| 35 | SYCA | SEAY CONTRACTING CO | | | SCAC4 |
| 36 | SYCB | SISLER LUMBER COMPANY INC | | | SCAC4 |
| 37 | SYCC | SYCAMORE SPECIALIZED CARRIERS INC | | | SCAC4 |
| 38 | SYCE | RAILROAD STORAGE & DRAYAGE INC | | | SCAC4 |
| 39 | SYCG | STONY CREEK TRUCKING LLC | | | SCAC4 |
| 40 | SYCH | SYMES, CHARLES | | | SCAC4 |
| 41 | SYCI | SYC LOGISTICS INC | | | SCAC4 |
| 42 | SYCJ | SOUTHERN DELIVERY | | | SCAC4 |
| 43 | SYCM | STEVESART AND IMAGERY | | | SCAC4 |
| 44 | SYCR | SAMY C TRANSPORT | | | SCAC4 |
| 45 | SYCT | STAR TOYS AND COLLECTIBLES | | | SCAC4 |
| 46 | SYCY | STEEL TOY CARRIERS LLC | | | SCAC4 |
| 47 | SYD | Air Yendis Limited | Callsign: Yendis, | Z | AVCODES |
| 48 | SYD | Flying Ambulance (Pty) Ltd t/a Aerocare | Callsign: Skydoctor, | ZA | AVCODES |
| 49 | SYDB | SYDIA BROS ENT LTD | | | SCAC4 |
| 50 | SYDE | STAT TRANSPORT SYSTEMS INC | | | SCAC4 |
| 51 | SYDM | SYNERGY MANUFACTURING INC | | | SCAC4 |
| 52 | SYDNEY | | City: Sydney | AUS | TRAFFIC |
| 53 | SYDNT | Sydney Trains | City: Sydney | AUS | TRAFFIC |
| 54 | SYDQ | SMITH MONUMENT COMPANY LTD | | | SCAC4 |
| 55 | SYDT | Sydtåg | Real: ST, 1991 - 1997 | S | TRAFFIC |
| 56 | SYE | Sheba Aviation | | YAR | AVCODES |
| 57 | SYE | Sheba Aviation | | | ICAO1 |
| 58 | SYEA | STINGRAY EXPRESS INC | | | SCAC4 |
| 59 | SYEC | STANLEY E INC | | | SCAC4 |
| 60 | SYEI | SCOYO TRANSPORT INC | | | SCAC4 |
| 61 | SYEK | SKYTEK EXPRESS INC | | | SCAC4 |
| 62 | SYEL | SNOOPY EXPRESS LLC | | | SCAC4 |
| 63 | SYEM | STC | | | SCAC4 |
| 64 | SYEN | SAIYEN TRANSPORT | | | SCAC4 |
| 65 | SYES | SPEEDWA | | | SCAC4 |
| 66 | SYET | SHIREY, ERNEST E TRUCKING | | | SCAC4 |
| 67 | SYF | Sky One Express Airlines, Inc. | Callsign: Sky First, | USA | AVCODES |
| 68 | SYF | Sky One Express Airlines | | | ICAO1 |
| 69 | SYFC | SPEEDY FREIGHT CARRIER INC | | | SCAC4 |
| 70 | SYFE | STANLEY FURNITURE CO INC | | | SCAC4 |
| 71 | SYFF | SMORGON STEEL RECYCLING INC | | | SCAC4 |
| 72 | SYFG | SECURITY FREIGHT SYSTEMS | | | SCAC4 |
| 73 | SYFI | SYSTEM FREIGHT INC | | | SCAC4 |
| 74 | SYFL | SOUTH BAY APPAREL INC | | | SCAC4 |
| 75 | SYFN | SYFAN LOGISTICS INC | | | SCAC4 |
| 76 | SYFO | SYFILCO LTD | | | SCAC4 |
| 77 | SYFR | STALEY FARMS | | | SCAC1 |
| 78 | SYFS | SNYDER FUEL SERVICE INC | | | SCAC4 |
| 79 | SYG | Synergy Aviation Ltd. | IATA: YD, Callsign: Synergy, IATA Prefix: 259, | GB | AVCODES |
| 80 | SYG | Synergy Aviation | | | ICAO1 |
| 81 | SYGA | SUNNY GROUP USA INC | | | SCAC4 |
| 82 | SYGC | SYNERGISTICS LLC | | | SCAC4 |
| 83 | SYGN | SYRACUSE GLASS COMPANY INC | | | SCAC4 |
| 84 | SYGP | SPECIALTY STORAGE COMPANY | | | SCAC4 |
| 85 | SYGS | S Y GRANI TOPS INC | | | SCAC4 |
| 86 | SYGT | SYNERGY TRANSPORTATION SYSTEMS INC | | | SCAC4 |
| 87 | SYGV | SKY LOGISTICS OF VIRGINIA LLC | | | SCAC4 |
| 88 | SYH | Sky Handling | | UA | AVCODES |
| 89 | SYHA | STONECOUNTRY WELSH INC | | | SCAC4 |
| 90 | SYHD | SPEEDY HEAVY DUTY HAULING | | | SCAC4 |
| 91 | SYHF | SHUEY & HOFFMAN FUELS INC | | | SCAC4 |
| 92 | SYHG | SYNCREON HOLDINGS INC | | | SCAC4 |
| 93 | SYHH | SYNCREON NORTH AMERICA INC (DIV OF | | | SCAC4 |
| 94 | SYHI | SYNCREON.US INC (DIV OF SYNCREON HO | | | SCAC4 |
| 95 | SYHJ | SYNCREON AMERICA INC (DIV OF SYNCRE | | | SCAC4 |
| 96 | SYHN | SYSTEME HUNTINGDON INC | | | SCAC4 |
| 97 | SYHT | SUNNY HILLS TOWING | | | SCAC4 |
| 98 | SYHW | SSANGYONG SHIPPING CO LTD | | | SCAC4 |
| 99 | SYI | Sonalysts, Inc. | | USA | AVCODES |
| 100 | SYI | Sonalysts | | | ICAO1 |
