| 1 | HH | Islandsflug HF | ICAO: ICB, Callsign: Icebird, IATA Prefix: 652, Designator HH recalled by IATA. Merged in Air Atlanta Icelandic. IATA designator changed from HT* | IS | AVCODES |
| 2 | HH | Hispania, S.A. | ICAO: HSL, Ceased operations on 15 July 1989. IATA designator changed from XX | E | AVCODES |
| 3 | HH | Somali Airlines | ICAO: SOM, Callsign: Somalair, | SO | AVCODES |
| 4 | HH | Limited Liability Company Qanot Sharq | ICAO: QNT, Callsign: Qanot Sharq, | UZ | AVCODES |
| 5 | HH | Taban Airlines | ICAO: TBN, Callsign: Taban Air, | IR | AVCODES |
| 6 | HH | Hjørring - Hørby | 1913 - 1953 | DK | jernbanen.dk |
| 7 | HH | HIMMELBERGER-HARRISON MANUFACTURING | | | PWRC |
| 8 | HH | | City: Hamburg | D | TRAFFIC |
| 9 | HHA | Atlantic Airlines de Honduras, S de R.L. | IATA: ZF, Callsign: Atlantic Honduras, Founded in 1991 by Atlantic Airlines of Nicaragua. Ceased Operations in October 2008. Company dissolved in 2009. | HN | AVCODES |
| 10 | HHA | Atlantic Airlines de Honduras | | | ICAO1 |
| 11 | HHA | Hamburger Hochbahn AG | City: Hamburg | D | TRAFFIC |
| 12 | HHAG | HURST HAULING | | | SCAC4 |
| 13 | HHAH | H & H TRANSPORTATION INC | | | SCAC4 |
| 14 | HHAL | HANSEN HAULING | | | SCAC4 |
| 15 | HHAN | HORSCH ANDERSON | | | SCAC4 |
| 16 | HHAR | HARVEY, HAROLD | | | SCAC4 |
| 17 | HHAT | HATCHETT TRANSPORTATION INC | | | SCAC4 |
| 18 | HHAU | HENRI HARSCH HH SA | | CH | BIC |
| 19 | HHAU | HENRI HARSCH HH SA | | | SCAC4 |
| 20 | HHAY | HUBKA HAY FARMS | | | SCAC4 |
| 21 | HHB | Helsingør - Hornbæk Banen (Hornbækbanen) | 1906 - 1916 | DK | jernbanen.dk |
| 22 | HHB | Hamburger Hafenbahn AG | Hamburg | D | privat-bahn.de |
| 23 | HHB | Helsingør - Hornbæk Banen (Hornbækbanen) | 1906 - 1916 | DK | TRAFFIC |
| 24 | HHB | Hamburger Hafenbahn | | DE | VKM |
| 25 | HHBAU | W.Hundhausen Bauunternehmen GmbH | | DE | VKM |
| 26 | HHBC | HBC HAMBURG BULK CARRIERS GMBH & CO | | | SCAC4 |
| 27 | HHBF | HHBULKERS FIVE LTD | | | SCAC4 |
| 28 | HHBK | H & H BROKERAGE | | | SCAC4 |
| 29 | HHBL | HENDRIK HUDSON BUS LINES INC | | | SCAC4 |
| 30 | HHBT | HUTTERVILLE HUTTERIAN BRETHREN | | | SCAC4 |
| 31 | HHCC | HYDRO TECH INC | | | SCAC4 |
| 32 | HHCE | H & H COOL EXPRESS LLC | | | SCAC4 |
| 33 | HHCG | HUNGERFORD HEATING/ COOLING | | | SCAC4 |
| 34 | HHCH | HH HAULING | | | SCAC4 |
| 35 | HHCL | HEADHAUL.COM LLC | | | SCAC4 |
| 36 | HHCO | HEINZ, H J COMPANY OF CANADA LTD | | | SCAC4 |
| 37 | HHCR | HIS & HERS COACHWAYS INC | | | SCAC4 |
| 38 | HHCS | HIGH HILLS COURIER SERVICE LIMITED | | | SCAC4 |
| 39 | HHCV | H & H CONTAINER SERVICES LLC | | | SCAC4 |
| 40 | HHCX | Flint Hills Resources LP | added 1/2009 | | NAKINA |
| 41 | HHCX | Huntsman LLC | added 7/2003; 7/2005; eliminated 1/2009 | | NAKINA |
| 42 | HHCX | Champlin Petroleum Co. | added 7/1965; 7/1965-4/1970; eliminated 4/1972 | | NAKINA |
| 43 | HHCX | Champlin Oil & Refining Co. | added 4/1957; 10/1957-4/1961; eliminated 7/1965 | | NAKINA |
| 44 | HHCX | Champlin Refining Co. | 7/1935-7/1954; eliminated 4/1957 | | NAKINA |
| 45 | HHCX | H.H.C. Equipment Co. | 7/1932 | | NAKINA |
| 46 | HHCX | Champlin Tank Car Co. | 7/1930 | | NAKINA |
| 47 | HHCX | Champlin Refining Co. | 8/1920-7/1923 | | NAKINA |
| 48 | HHCX | Champlin Refining Co. | 4/38-1/52; eliminated 4/57 | | NRHS |
| 49 | HHCX | Champlin Oil & Refining Co. | added 4/57; 10/57-4/61; eliminated 7/65 | | NRHS |
| 50 | HHCX | Champlin Petroleum Co. | added 7/65; 7/65-4/70; eliminated 4/72 | | NRHS |
| 51 | HHCX | *CHAMPLIN REFINING CO. [H.H.C. EQUIPMENT CO.] | | | PWRC |
| 52 | HHCX | +HUNTSMAN LLC | | | PWRC |
| 53 | HHCX | Huntsman | | | RSRV |
| 54 | HHCX | CHAMPLIN PETROLEUM CO | | | SCAC3 |
| 55 | HHCX | HUNTSMAN LLC | | | SCAC4 |
| 56 | HHDC | HAWG HAULING & DISPOSAL LLC | | | SCAC4 |
| 57 | HHDK | Hjørring - Hørby | Real: HH, 1913 - 1953 | DK | TRAFFIC |
| 58 | HHDR | HIGH DESERT TRANSPORT | | | SCAC4 |
| 59 | HHE | Heli-holland B.V. | Callsign: Heli Holland, | NL | AVCODES |
| 60 | HHE | Heli-Holland | | | ICAO1 |
| 61 | HHE | Freunde der Halle-Hettstedter Eisenbahn e.V. | | DE | VKM |
| 62 | HHEART | Hokkaido Heart Bus | | J | TRAFFIC |
| 63 | HHEB | HILL HOPPER EXPRESS INC | | | SCAC4 |
| 64 | HHEI | HAWK HOLLOW EXPRESS INC | | | SCAC4 |
| 65 | HHEP | H & H EXPRESS LLC | | | SCAC4 |
| 66 | HHER | HIRSCHE HEREFORDS | | | SCAC4 |
| 67 | HHES | HILL, HOLLY EXPRESS LOGISTICS INC | | | SCAC4 |
| 68 | HHEX | H & H Engineering Construction, Inc. | 7/2000-7/2005 (not listed) | | NAKINA |
| 69 | HHEX | H & H Engineering Construction, Inc. | Jul-00 | | NRHS |
| 70 | HHEX | H & H ENGINEERING CONSTRUCTION, INC. | | | PWRC |
| 71 | HHEX | H and H Engineering Construction | | | RSRV |
| 72 | HHFD | H & H FISHERIES LTD | | | SCAC4 |
| 73 | HHFE | HUTCH FUEL OIL | | | SCAC4 |
| 74 | HHFL | H & H FREIGHT LINES INC | | | SCAC4 |
| 75 | HHFT | H & H FARMS | | | SCAC4 |
| 76 | HHG | Hanergy Jet Co,o Ltd. | Callsign: Hanergy Jet, | PRC | AVCODES |
| 77 | HHGB | Helsingør - Hornbæk - Gilleleje Banen (Hornbækbanen) | 1916 - 2001 | DK | jernbanen.dk |
| 78 | HHGB | Helsingør - Hornbæk - Gilleleje Banen (Hornbækbanen) | 1916 - 2001 | DK | TRAFFIC |
| 79 | HHGE | HOEPFNER, HANS GUENTHER | | | SCAC4 |
| 80 | HHGI | HH & G INC | | | SCAC4 |
| 81 | HHH | Helicsa | Callsign: Helicsa, Merged into Inaer. | E | AVCODES |
| 82 | HHH | Air Hawaii | IATA: XK, Ceased operations | USA | AVCODES |
| 83 | HHH | H H Helicopters Ltd | Callsign: Corinium, | GB | AVCODES |
| 84 | HHH | Helicsa | | | ICAO1 |
| 85 | HHHA | H & H HAULERS | | | SCAC4 |
| 86 | HHHF | HALPINS FUEL SERVICE INC | | | SCAC4 |
| 87 | HHHL | HAWKINS HEAVY HAULING SERVICE LLC | | | SCAC4 |
| 88 | HHHQ | HAWK HIGH HAULAGE INC | | | SCAC4 |
| 89 | HHHR | HERITAGE HEAVY HAUL INC | | | SCAC4 |
| 90 | HHHT | HENDERSON HEAVY HAUL TRUCKING INC | | | SCAC4 |
| 91 | HHHU | KTG-KRAFTWAGEN-TRANSPORT GESMBH | | | SCAC3 |
| 92 | HHHX | Xcel Energy | added 1/2006 | | NAKINA |
| 93 | HHHX | Public Service Co. of Colorado | added 10/2000; eliminated 10/2002; 7/2005 (not listed) | | NAKINA |
| 94 | HHHX | Public Service Co. of Colorado | added 10/2000 | | NRHS |
| 95 | HHHX | XCEL ENERGY [PUBLIC SERVICE CO. OF COLORADO] | | | PWRC |
| 96 | HHHX | Public Service of Colorado | | | RSRV |
| 97 | HHHX | XCEL ENERGY | | | SCAC4 |
| 98 | HHHY | HEARTLAND HEAVY HAUL INC | | | SCAC4 |
| 99 | HHI | Hamburg International Luftverkehirsgesellschaft mbH | IATA: 4R, Callsign: Hamburg Jet, Ceased operations on 20 October 2010 and filed for Bankruptcy | D | AVCODES |
| 100 | HHI | Hamburg International | IATA: 4R | | ICAO1 |
