| 1 | ZT | Voronezhavia | ICAO: VRN, Callsign: Voronezhavia, Designator ZT recalled by IATA | RUS | AVCODES |
| 2 | ZT | Titan Airways Ltd. | ICAO: AWC, Callsign: Zap, IATA Prefix: 858, ICAO designator changed from TOT | GB | AVCODES |
| 3 | ZT | Air Zambezi | ICAO: TZT, Callsign: Zambezi, Designator ZT reinstated by IATA | ZW | AVCODES |
| 4 | ZT | Satena, Servicios de Aeronavegacion A Territorios Nac | ICAO: NSE, Callsign: Satena, Designator recalled by IATA | CO | AVCODES |
| 5 | ZT | Air Zambezi | ICAO: TZT, Callsign: Zambezi, Designator ZT recalled by IATA | ZW | AVCODES |
| 6 | ZT | Thai EastarJet Co., Ltd. | ICAO: ESS, Callsign: Thai Star, | T | AVCODES |
| 7 | ZT | ZAGREBTRANS d.o.o. | | HR | VKM |
| 8 | ZTB | Zakłady Tłuszczowe w Bodaczowie Sp. z o.o. | | PL | VKM |
| 9 | ZTBIE | Zakłady Tłuszczowe “BIELMAR” Sp. z o.o. | | PL | VKM |
| 10 | ZTBK | ZEUS TRUCK BROKERS LLC | | | SCAC4 |
| 11 | ZTCU | SUZHOU ZHENGBANG TONGYUAN LOGISTICS EQUIPMENT CO., LTD. | | PRC | BIC |
| 12 | ZTEE | ZEE TEE ENTERPRISES | | | SCAC4 |
| 13 | ZTEH | ZERO THREE (03) EQUIPMENT HAULING L | | | SCAC4 |
| 14 | ZTEN | TENNESSEE CHEMICAL CO. | | | PWRC |
| 15 | ZTEN | ZIMMERMAN TRUCKING & EXCAVATING INC | | | SCAC4 |
| 16 | ZTEU | AZTEC LEASING CORPORATION | | | PWRC |
| 17 | ZTEU | Aztec Leasing Corporation | | | RSRV |
| 18 | ZTID | Z TRANSPORTATION INC | | | SCAC4 |
| 19 | ZTIK | ZOJAN TRANSPORT INC | | | SCAC4 |
| 20 | ZTIQ | ZEN TRANSPORT INC | | | SCAC4 |
| 21 | ZTIT | ZWALD TRANSPORT INC | | | SCAC4 |
| 22 | ZTK | ZAKŁAD TRANSPORTU KOLEJOWEGO „SIARKOPOL” Sp. z o.o. | | PL | VKM |
| 23 | ZTKRU | Zakłady Tłuszczowe “Kruszwica” S.A. | | PL | VKM |
| 24 | ZTKU | NIJMAN/ZEETANK INT TANKTRANSPORTEN BV | | NL | BIC |
| 25 | ZTLB | ZEPHANIAH TRANSPORT LLC | | | SCAC4 |
| 26 | ZTLC | ZION TRANSPORTATION, LLC | | | SCAC4 |
| 27 | ZTLD | ZUMBA TRANSPORTATION LLC | | | SCAC4 |
| 28 | ZTLK | ZACK TRUCK LINES | | | SCAC4 |
| 29 | ZTLL | Z TRANSPORT & LOGISTICS LLC | | | SCAC4 |
| 30 | ZTLX | Zenith Tank Line | 8/1920 | | NAKINA |
| 31 | ZTLX | Ziol Tank Line | added 7/1973; 1/1975-1/1980; eliminated 1/1991; 1/1994 (not listed); added 7/1999; 7/2000; eliminated 10/2003 | | NAKINA |
| 32 | ZTLX | Ziol Tank Line | added 7/73; 1/75-1/80; eliminated 1/91; 1/94; added 7/99; 7/2000 | | NRHS |
| 33 | ZTLX | *ZENITH TANK LINE | | | PWRC |
| 34 | ZTLX | *ZIOL TANK LINE | | | PWRC |
| 35 | ZTLX | Ziol Tank Line | | | RSRV |
| 36 | ZTMG | ZORROS TRUCKING | | | SCAC4 |
| 37 | ZTNU | ZITON A/S CVR 24620417 | | DK | BIC |
| 38 | ZTPN | ZEMA TRANSPORT INC | | | SCAC4 |
| 39 | ZTRC | Z TRANSPORTATION INC | | | SCAC4 |
| 40 | ZTRD | ZELT TRANSPORT | | | SCAC4 |
| 41 | ZTRF | ZAVALA TRANSFER | | | SCAC4 |
| 42 | ZTRI | Z TRANS INC | | | SCAC4 |
| 43 | ZTRK | Z TRUCKING CO | | | SCAC1 |
| 44 | ZTRK | Z TRUCKING LLC | | | SCAC4 |
| 45 | ZTRL | ZORROS TRUCKLINE | | | SCAC4 |
| 46 | ZTRN | Z TRANS INC | | | SCAC4 |
| 47 | ZTRP | ZARIC TRANSPORTATION | | | SCAC4 |
| 48 | ZTSC | ZIM TRANSPORT SERVICES INC | | | SCAC4 |
| 49 | ZTSE | Z TRANS SERVICES INC | | | SCAC4 |
| 50 | ZTSU | ZHONGTUO CONTAINER TECHNOLOGY CO., LTD | | PRC | BIC |
| 51 | ZTSV | ZIM TRANSPORT SERVICES INC | | | SCAC4 |
| 52 | ZTT | Transporttechnik Zeller KG | | A | TRAFFIC |
| 53 | ZTTU | Zhytomyrske Tramvaino-Troleybusne Upravlinnya | City: Zhytomyr | UA | TRAFFIC |
| 54 | ZTTX | Trailer Train Co. | added 4/1966; eliminated 1/1992 | | NAKINA |
| 55 | ZTTX | Trailer Train Co. (FM flat cars for general service. These cars are equipped with 15 stake pockets per side, total 30 stake pockets) | 10/1966-10/1968 | | NAKINA |
| 56 | ZTTX | Trailer Train Co./TTX Co. (flat cars equipped with 30 stake pockets, 15 per side; for transporting long poles) | 4/1970-7/2000 | | NAKINA |
| 57 | ZTTX | Trailer Train Co. | added 4/1966; eliminated 1/1992 | | NAKINA |
| 58 | ZTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 59 | ZTTX | Trailer Train Co. | added 4/66; eliminated 1/92 | | NRHS |
| 60 | ZTTX | Trailer Train Co. (FM flat cars for general service. These cars are equipped with 15 stake pockets per side, total 30 stake pockets) | 10/66-10/68 | | NRHS |
| 61 | ZTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 62 | ZTTX | Trailer Train Co. (flat cars equipped with 30 stake pockets, 15 per side; for transporting long poles) | 1/75-1/80; eliminated 1/92 | | NRHS |
| 63 | ZTTX | TTX Co. (flat cars equipped with 30 stake pockets, 15 per side; for transporting long poles) | added 1/92; 1/94-7/2000 | | NRHS |
| 64 | ZTTX | TTX COMPANY (TRAILER TRAIN COMPANY) | | | PWRC |
| 65 | ZTTX | Trailer Train (TTX Corporation) | | | RSRV |
| 66 | ZTTX | TTX COMPANY | | | SCAC4 |
| 67 | ZTUK | Z TRUCKING INC | | | SCAC4 |
| 68 | ZTUS | TEXACO CHEMICAL (CHEVRON-TEXACO) | | | PWRC |
