| 1 | HT | Modiluft Limited | ICAO: MOD, Callsign: Modiluft, IATA Prefix: 548, Ceased operations in 1996. AOC transferred to Royal Airways t/a SpiceJet | IND | AVCODES |
| 2 | HT | Islandsflug HF | ICAO: ICB, Callsign: Icebird, IATA designator changed to HH | IS | AVCODES |
| 3 | HT | Airwork (New Zealand) Ltd. | ICAO: PST, Callsign: Post, Designator HT recalled by IATA | NZ | AVCODES |
| 4 | HT | Air Tchad, Société de Transports Aériens | ICAO: HTT, Callsign: Hotel Tango, Designator HT recalled by IATA | TCH | AVCODES |
| 5 | HT | Hellenic Imperial Airways | ICAO: IMP, Callsign: Imperial, IATA Prefix: 570, Founded in May 2006. Ceased operations in 2012. | GR | AVCODES |
| 6 | HT | Ningxia Cargo Airlines Co., Ltd. | ICAO: HTK, Callsign: Lingbird, IATA Prefix: 669, | PRC | AVCODES |
| 7 | HT | Air Horizont | ICAO: HAT, Callsign: Sky Runner, | M | AVCODES |
| 8 | HT | Tianjin Air Cargo Co., Ltd. | ICAO: CTJ, Callsign: Tianjin Cargo, IATA Prefix: 877, | PRC | AVCODES |
| 9 | HT | Howard Terminal | 1/1975 | | NAKINA |
| 10 | HT | Howard Terminal | Jan-75 | | NRHS |
| 11 | HT | HOWARD TERMINAL RAILWAY | | | PWRC |
| 12 | HT | Hull Trains | | UK | VKM |
| 13 | HTA | Heli-Trans AS | Callsign: Scanbird, Designator 5H recalled by IATA | N | AVCODES |
| 14 | HTA | Heli-Trans AS | IATA: 5H, Callsign: Scanbird, Designator 5H recalled by IATA | N | AVCODES |
| 15 | HTA | Hawthorne Aviation | Callsign: Air Richmond, | USA | AVCODES |
| 16 | HTA | Helitrans AS | IATA: 9I, Callsign: Scanbird, Designator 9I recalled by IATA. | N | AVCODES |
| 17 | HTA | Heli Transair European Air Services GmbH | Callsign: Heli Transair, | D | AVCODES |
| 18 | HTA | Helitrans | | | ICAO1 |
| 19 | HTAA | HAMILTON TRANSPORT LLC | | | SCAC4 |
| 20 | HTAB | HIND TRANSPORT | | | SCAC4 |
| 21 | HTAC | HART'S TERMINAL&CARTAGE CO | | | SCAC1 |
| 22 | HTAC | HIGHWAY TRANSPORT CHEMICAL LLC | | | SCAC4 |
| 23 | HTAE | HTI LOGISTICS LLC | | | SCAC4 |
| 24 | HTAF | | | RH | TRAFFIC |
| 25 | HTAK | HALBERSLEBEN TRUCKING | | | SCAC4 |
| 26 | HTAM | HIGHLAND TRANSPORT | | | SCAC1 |
| 27 | HTAM | HIGHLAND TRANSPORT (DIV OF TFI TRAN | | | SCAC4 |
| 28 | HTAN | HULSE FARMS TRUCKING INC | | | SCAC4 |
| 29 | HTAQ | HAMES TRUCKING CARRIER, INC. | | | SCAC4 |
| 30 | HTAR | HITACHI TRANSPORT SYSTEM (AMERICA) | | | SCAC4 |
| 31 | HTAS | HI-TECH AIR SHIPPING INC | | | SCAC4 |
| 32 | HTAW | HAGEN TRUCKING INC | | | SCAC4 |
| 33 | HTAY | HOUSTON INTERNATIONAL ENTERPRISES I | | | SCAC4 |
| 34 | HTB | Helix-Craft Aviation | Callsign: Helix-Craft, | PA | AVCODES |
| 35 | HTB | Horsens - Tørring Banen (Tørringbanen) | 1891 - 1929 | DK | jernbanen.dk |
| 36 | HTB | Hörseltalbahn GmbH | Eisenach (Connex-Gruppe > Veolia Verkehr > Captrain) | D | privat-bahn.de |
| 37 | HTB | Hellertalbahn GmbH | Betzdorf | D | privat-bahn.de |
| 38 | HTB | Hörseltalbahn, Eisenach | | D | TRAFFIC |
| 39 | HTB | Hörseltalbahn | | DE | VKM |
| 40 | HTBB | HUGHES, B & B TRUCKING LLC | | | SCAC4 |
| 41 | HTBC | HELMBOLT TRUCKING INC | | | SCAC4 |
| 42 | HTBC | Hokkaido Takushoku Bus Co.,Ltd. | | J | TRAFFIC |
| 43 | HTBD | HUNT TRANSPORTATION INC (BROKERAGE | | | SCAC4 |
| 44 | HTBD | Horsens - Tørring Banen (Tørringbanen) | Real: HTB, 1891 - 1929 | DK | TRAFFIC |
| 45 | HTBF | HEFFERNAN TRUCKING LLC | | | SCAC4 |
| 46 | HTBI | HOT OIL TRANSPORT | | | SCAC4 |
| 47 | HTBP | HT LOGISTICS LLC | | | SCAC4 |
| 48 | HTBQ | HERSHEY TRANSPORT | | | SCAC4 |
| 49 | HTBR | H T BAR INC | | | SCAC4 |
| 50 | HTBT | HEIL TRUCK BROKERAGE INC | | | SCAC4 |
| 51 | HTBV | HERBERT TRANSPORTATION INC | | | SCAC4 |
| 52 | HTBW | HAMPTON TRANSPORT LLC | | | SCAC4 |
| 53 | HTC | Haiti Trans Air, S.A. | Callsign: Haiti Transair, | RH | AVCODES |
| 54 | HTC | Haiti Trans Air, S.A. | IATA: TV, Callsign: Haiti Transair, Designator TV recalled by IATA | RH | AVCODES |
| 55 | HTC | Haiti Trans Air | | | ICAO1 |
| 56 | HTC | Houston & Texas Central | | USA | TRAFFIC |
| 57 | HTCD | HATCHER DAIRY FARM | | | SCAC4 |
| 58 | HTCE | H T C EXPRESS INC | | | SCAC4 |
| 59 | HTCG | HERRERA TRUCKING | | | SCAC4 |
| 60 | HTCH | HATCHER TRUCKING COMPANY | | | SCAC1 |
| 61 | HTCH | HATCHER TRUCKING COMPANY, INCORPORA | | | SCAC4 |
| 62 | HTCI | HUTCHCRAFT VAN SVC INC | | | SCAC4 |
| 63 | HTCJ | HEWITT TRUCKING COMPANY | | | SCAC4 |
| 64 | HTCL | HODGE TRUCKING CO INC | | | SCAC4 |
| 65 | HTCM | H2O COMPOSITES INC | | | SCAC4 |
| 66 | HTCN | HTC TRUCKING LLC | | | SCAC4 |
| 67 | HTCO | HETCO MOVING SYSTEMS INC | | | SCAC4 |
| 68 | HTCP | H T C | | | SCAC4 |
| 69 | HTCR | HURMAN TRUCKING COMPANY | | | SCAC4 |
| 70 | HTCU | HALDOR TOPSOE A/S | | DK | BIC |
| 71 | HTCU | HALDOR TOPSOE A/S | | | SCAC4 |
| 72 | HTCV | HELLENIC TANKERS CO LTD | | | SCAC4 |
| 73 | HTCW | HUTCHISON TRUCKING INC | | | SCAC4 |
| 74 | HTCX | General Electric Rail Services Corp. | added 1/2000; 7/2000-7/2005 | | NAKINA |
| 75 | HTCX | General Electric Railcar Services Corp. | added 1/1994; eliminated 1/2000 | | NAKINA |
| 76 | HTCX | Chrysler Rail Transportation Corp. | added 4/1991; eliminated 1/1994 | | NAKINA |
| 77 | HTCX | Transportation Corp. of America | added 4/1974; 1/1975-1/1980; eliminated 4/1991 | | NAKINA |
| 78 | HTCX | Arthur Equipment Co. | added 10/1971; eliminated 4/1974 | | NAKINA |
| 79 | HTCX | Harbor Tank Line Co. | 7/1935-4/1970; eliminated 10/1971 | | NAKINA |
| 80 | HTCX | Haffner Thrall Car Co. (Harbor Tank Line Co.) | 7/1930-7/1932 | | NAKINA |
| 81 | HTCX | Harbor Tank Line Co. | 4/38-4/70; eliminated 10/71 | | NRHS |
| 82 | HTCX | Arthur Equipment Co. | added 10/71 | | NRHS |
| 83 | HTCX | Transportation Corp. of America | 1/75-1/80; eliminated 4/91 | | NRHS |
| 84 | HTCX | Chrysler Rail Transportation Corp. | added 4/91; eliminated 1/94 | | NRHS |
| 85 | HTCX | General Electric Railcar Services Corp. | added 1/94; eliminated 1/2000 | | NRHS |
| 86 | HTCX | General Electric Rail Services Corp. | added 1/2000; 7/2000 | | NRHS |
| 87 | HTCX | (NATX) GENERAL ELECTRIC RAIL SERVICES CORPORATION [CHRYSLER RAIL TRANSPORTATION CORP; TRANSPORTATION CORP. OF AMERICA; ARTHUR EQUIPMENT CO.; HARBOR TANK LINE; HAFFNER THRALL CAR CO.] | | | PWRC |
| 88 | HTCX | Transportation Corporation of America (GE Rail Services Corporation) | | | RSRV |
| 89 | HTCX | GENERAL ELECTRIC RAILCAR SERVICES C | | | SCAC4 |
| 90 | HTCY | HANOVER TRANSFER CO | | | SCAC1 |
| 91 | HTCY | HASTINGS TRUCK COMPANY INC | | | SCAC4 |
| 92 | HTCZ | HIBBING TACONITE CO. | | | PWRC |
| 93 | HTDA | HENDERSON TRUCKING INC | | | SCAC4 |
| 94 | HTDD | HUNTLEY TRUCKING CO | | | SCAC4 |
| 95 | HTDF | HARTILL HEAVY HAUL INC | | | SCAC4 |
| 96 | HTDG | HEADWATERS TRUCKING INC | | | SCAC4 |
| 97 | HTDI | HAGAN TRANSPORT LLC | | | SCAC4 |
| 98 | HTDL | H T D TRUCKING | | | SCAC4 |
| 99 | HTDN | HERNANDEZ TRUCKING | | | SCAC4 |
| 100 | HTDO | HOFER TRUCKING | | | SCAC4 |
