| 1 | HHH | Helicsa | Callsign: Helicsa, Merged into Inaer. | E | AVCODES |
| 2 | HHH | Air Hawaii | IATA: XK, Ceased operations | USA | AVCODES |
| 3 | HHH | H H Helicopters Ltd | Callsign: Corinium, | GB | AVCODES |
| 4 | HHH | Helicsa | | | ICAO1 |
| 5 | HHHA | H & H HAULERS | | | SCAC4 |
| 6 | HHHF | HALPINS FUEL SERVICE INC | | | SCAC4 |
| 7 | HHHL | HAWKINS HEAVY HAULING SERVICE LLC | | | SCAC4 |
| 8 | HHHQ | HAWK HIGH HAULAGE INC | | | SCAC4 |
| 9 | HHHR | HERITAGE HEAVY HAUL INC | | | SCAC4 |
| 10 | HHHT | HENDERSON HEAVY HAUL TRUCKING INC | | | SCAC4 |
| 11 | HHHU | KTG-KRAFTWAGEN-TRANSPORT GESMBH | | | SCAC3 |
| 12 | HHHX | Xcel Energy | added 1/2006 | | NAKINA |
| 13 | HHHX | Public Service Co. of Colorado | added 10/2000; eliminated 10/2002; 7/2005 (not listed) | | NAKINA |
| 14 | HHHX | Public Service Co. of Colorado | added 10/2000 | | NRHS |
| 15 | HHHX | XCEL ENERGY [PUBLIC SERVICE CO. OF COLORADO] | | | PWRC |
| 16 | HHHX | Public Service of Colorado | | | RSRV |
| 17 | HHHX | XCEL ENERGY | | | SCAC4 |
| 18 | HHHY | HEARTLAND HEAVY HAUL INC | | | SCAC4 |
