| 1 | HYD | Hydro-Quebec | IATA: 0Q, Callsign: Hydro, Designator 0Q* recalled by IATA. | CDN | AVCODES |
| 2 | HYD | Hydro-Quebec | Callsign: Hydro, Designator 0Q* recalled by IATA. | CDN | AVCODES |
| 3 | HYD | Hydro-QuA~©bec | | | ICAO1 |
| 4 | HYDA | HYDER TRANSPORTATION LLC | | | SCAC4 |
| 5 | HYDB | HYDER BOYS TRANSPORT LLC | | | SCAC4 |
| 6 | HYDC | HAYDEN TRANSPORTATION LLC | | | SCAC4 |
| 7 | HYDD | HIGIENICOS Y DESECHABLES DEL BAJIO | | | SCAC4 |
| 8 | HYDG | HYDE, GENE TRUCKING CO INC | | | SCAC4 |
| 9 | HYDK | HAYDUK ENTERPRISES INC | | | SCAC4 |
| 10 | HYDL | HYDE, GENE LOGISTICS INC | | | SCAC4 |
| 11 | HYDN | HAYDEN TRANSPORT INC | | | SCAC4 |
| 12 | HYDP | HYDRO TECHNOLOGIES (CANADA) INC | | | SCAC4 |
| 13 | HYDR | HYDRAULICS UNLIMITED | | | SCAC4 |
| 14 | HYDR | Hydrema Baumaschinen GmbH | | DE | VKM |
| 15 | HYDS | HYDROUSSA SHIPPING CO. S A | | | SCAC4 |
| 16 | HYDU | XINJIANG HONGYUNDA FREIGHT INTERNATIONAL CO., LTD. | | PRC | BIC |
| 17 | HYDU | HYDE SHIPPING | | | SCAC1 |
| 18 | HYDU | Hyundai | | | SCAC2 |
| 19 | HYDU | AMPHIBIOUS CONTAINERS LEASING LTD | | | SCAC4 |
| 20 | HYDX | Praxair, Inc. | added 1/1993; 1/1994-7/2005 | | NAKINA |
| 21 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | eliminated 1/1993 | | NAKINA |
| 22 | HYDX | Union Carbide Corp. | added 5/1983 | | NAKINA |
| 23 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | eliminated 5/1983 | | NAKINA |
| 24 | HYDX | Union Carbide Corp., Chemicals and Plastics Division | added 10/1980 | | NAKINA |
| 25 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | added 7/1980 | | NAKINA |
| 26 | HYDX | Union Carbide Corp. | eliminated 10/1980 | | NAKINA |
| 27 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | added 7/1980 | | NAKINA |
| 28 | HYDX | Union Carbide Corp., Chemicals and Plastics Division | added 1/1979; 1/1980; eliminated 7/1980 | | NAKINA |
| 29 | HYDX | Union Carbide Corp., Chemicals and Plastics Operations Division | added 1/1968; 4/1970-1/1975; eliminated 1/1979 | | NAKINA |
| 30 | HYDX | Union Carbide Corp., Chemicals and Plastics | added 10/1967; eliminated 1/1968 | | NAKINA |
| 31 | HYDX | Union Carbide Corp., Chemicals Division | added 7/1961; 7/1965-10/1966; eliminated 10/1967 | | NAKINA |
| 32 | HYDX | Union Carbide Corp., Chemicals Division | 7/65-10/66; eliminated 10/67 | | NRHS |
| 33 | HYDX | Union Carbide Corp., Chemicals and Plastics | added 10/67; eliminated 1/68 | | NRHS |
| 34 | HYDX | Union Carbide Corp., Chemicals and Plastics Operations Division | added 1/68; 4/70-1/75; eliminated 1/79 | | NRHS |
| 35 | HYDX | Union Carbide Corp., Chemicals and Plastics Division | added 1/79; 1/80; eliminated 7/80 | | NRHS |
| 36 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | added 7/80 | | NRHS |
| 37 | HYDX | Union Carbide Corp. | eliminated 10/80 | | NRHS |
| 38 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | added 7/80 | | NRHS |
| 39 | HYDX | Union Carbide Corp., Chemicals and Plastics Division | added 10/80 | | NRHS |
| 40 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | eliminated 5/83 | | NRHS |
| 41 | HYDX | Union Carbide Corp. | added 5/83 | | NRHS |
| 42 | HYDX | Union Carbide Corp., Chemicals and Plastics Co., Inc. | eliminated 1/93 | | NRHS |
| 43 | HYDX | Praxair, Inc. | added 1/93; 1/94-7/2000 | | NRHS |
| 44 | HYDX | (UCOX) PRAXAIR, INC. [UNION CARBIDE CORP.] | | | PWRC |
| 45 | HYDX | Union Carbide Corporation (Praxair) | | | RSRV |
| 46 | HYDX | PRAXAIR, INC. | | | SCAC4 |