| 1101 | UNDO | UNITED OIL PACKERS INC | | | SCAC4 |
| 1102 | UNDU | UNITAINER TRADING GMBH | | D | BIC |
| 1103 | UNDU | UNITAINER TRADING GMBH | | | SCAC4 |
| 1104 | UNDV | UNRAU, ABE J | | | SCAC4 |
| 1105 | UNDY | UNIQUE TRUCKING LTD | | | SCAC4 |
| 1106 | UNE | Aerolineas Universal S.A. | Callsign: Aeroune, Never started operations in 2001. | CO | AVCODES |
| 1107 | UNEC | UNIVERSITY CORP | | | SCAC1 |
| 1108 | UNER | UNITED EXPRESS | | | SCAC4 |
| 1109 | UNES | UNITY EXPRESS | | | SCAC4 |
| 1110 | UNEX | UNEX a.s. | | CZ | VKM |
| 1111 | UNEZ | UNION ELECTRIC | | | PWRC |
| 1112 | UNF | Union Flights | Callsign: Union Flights, | USA | AVCODES |
| 1113 | UNF | Union Flights | | | ICAO1 |
| 1114 | UNFA | UNKNOWN FOREIGN AIR CARRIER | | | SCAC1 |
| 1115 | UNFC | UNIVERSAL FOODS CORPORATION | | | SCAC1 |
| 1116 | UNFC | UNION AFRICA LINE | | | SCAC4 |
| 1117 | UNFE | UNI-FAB ENCLOSURES | | | SCAC4 |
| 1118 | UNFF | UNITED TRAFFIC SERVICES INC | | | SCAC4 |
| 1119 | UNFN | UNITED INTERMODE INC | | | SCAC4 |
| 1120 | UNFO | UNITED FOODS INC (FREEZER QUEEN FOO | | | SCAC4 |
| 1121 | UNFQ | UNFI | | | SCAC4 |
| 1122 | UNFU | UNIFEEDER FZCO | | UAE | BIC |
| 1123 | UNFW | UNION FREIGHTWAYS | | | SCAC4 |
| 1124 | UNFX | American Railcar Industries | added 10/2006 | | NAKINA |
| 1125 | UNFX | AMERICAN RAILCAR INDUSTRIES | | | PWRC |
| 1126 | UNFX | AMERICAN RAILCAR INDUSTRIES | | | SCAC4 |
| 1127 | UNGD | UNITED GLOBAL LOGISTICS INC | | | SCAC4 |
| 1128 | UNGI | UNIGAS INTERNATIONAL | | | SCAC4 |
| 1129 | UNGL | UNIGLORY | | | SCAC1 |
| 1130 | UNGN | UNIQUE TOOL & GAUGE INC | | | SCAC4 |
| 1131 | UNHS | UNISHIPPERS | | | SCAC4 |
| 1132 | UNI | United Air Charters | Callsign: Unitair, ICAO designator changed to UAC | ZW | AVCODES |
| 1133 | UNI | Community Express Airlines Ltd. | IATA: 5V, Callsign: Community, Ceased operations. | GB | AVCODES |
| 1134 | UNI | Universal Airlines | LCC of Air Europa | E | AVCODES |
| 1135 | UNI | Unicair GmbH | Callsign: Unicair, | D | AVCODES |
| 1136 | UNI | Unity Railways Co. | 1/1975-1/1980; eliminated 7/1986 | | NAKINA |
| 1137 | UNI | Unity Railways Co. | 1/75-1/80; eliminated 7/86 | | NRHS |
| 1138 | UNI | UNITY RAILWAYS | | | PWRC |
| 1139 | UNI | Unity Railways | | | RSRV |
| 1140 | UNI | UNIFERR Srl. | | I | TRAFFIC |
| 1141 | UNIA | UNITED AMERICAN LINES | | | SCAC4 |
| 1142 | UNIB | University Bus | | GB | TRAFFIC |
| 1143 | UNIC | UNITED TRUCKING COMPANY | | | SCAC4 |
| 1144 | UNICZ | UNILEASING a.s. | | CZ | VKM |
| 1145 | UNID | UNITED MOVING AND STORAGE INC | | | SCAC4 |
| 1146 | UNIDO | Unipetrol Doprava a.s. | | CZ | TRAFFIC |
| 1147 | UNIDO | UNIPETROL DOPRAVA, a.s. | | CZ | VKM |
| 1148 | UNIE | UNIEXPRESS TRANSPORTATION | | | SCAC4 |
| 1149 | UNIF | UNIFILT CORPORATION | | | SCAC4 |
| 1150 | UNIG | UNIFI INC | | | SCAC4 |
| 1151 | UNIH | UNITED HAULING CORPORATION | | | SCAC4 |
| 1152 | UNIK | UNITED TRANSPORT TANK CONTAINERS IN | | | SCAC4 |
| 1153 | UNIM | UNIVERSAL MAIL DELIVERY SERVICE | | | SCAC1 |
| 1154 | UNIM | UNIVERSAL MAIL DELIVERY SERVICE | | | SCAC4 |
| 1155 | UNIN | UNIONDALE HOLDINGS | | | SCAC4 |
| 1156 | UNIO | UNITED OIL HEAT INC | | | SCAC4 |
| 1157 | UNIP | UNISHIPPERS | | | SCAC4 |
| 1158 | UNIQ | UNIQUE TRUCKING EXPRESS INC | | | SCAC4 |
| 1159 | UNIR | UNISHIPPERS | | | SCAC4 |
| 1160 | UNIS | UNITED STATES ARMORED CO | | | SCAC4 |
| 1161 | UNIU | UNITAS CONTAINERS LIMITED | | BM | BIC |
| 1162 | UNIU | UNITAS SERVICES LTD | | | SCAC4 |
| 1163 | UNIW | UNIWORLD LOGISTICS PTE LTD | | | SCAC4 |
| 1164 | UNIWORLD | Uniworld Tours Inc. | | USA | TRAFFIC |
| 1165 | UNIX | United Protective Car Co. | 7/1935 | | NAKINA |
| 1166 | UNIX | Unigas, Inc. | added 7/1962; 7/1965-4/1970; eliminated 7/1971 | | NAKINA |
| 1167 | UNIX | Unified Environmental Services Group, LLC | 7/2005 (not listed) | | NAKINA |
| 1168 | UNIX | Unigas, Inc. | 7/65-4/70 | | NRHS |
| 1169 | UNIX | *UNIGAS, INC. | | | PWRC |
| 1170 | UNIX | +UNIFIED ENVIRONMENTAL SERVICES GROUP, LLC | | | PWRC |
| 1171 | UNIX | UNIFIED ENVIRONMENTAL SERVICES GROU | | | SCAC4 |
| 1172 | UNIY | UNITED DISTRIBUTION SERVICES INC | | | SCAC4 |
| 1173 | UNIZ | UNITED INDUSTRIES | | | PWRC |
| 1174 | UNJ | Universal Jet | | | ICAO1 |
| 1175 | UNJT | UNDERWOOD, JOE TRUCKING INC | | | SCAC4 |
| 1176 | UNKN | UNKNOWN VESSEL | | | SCAC1 |
| 1177 | UNKN | UNKNOWN CARRIER(FOR SEA,RAIL,TRUCK) | | | SCAC4 |
| 1178 | UNKO | UNITED WAREHOUSE CO | | | SCAC4 |
| 1179 | UNLA | UNIVERSAL CARTAGE LLC | | | SCAC4 |
| 1180 | UNLO | UNITED NATION LOGISTICS | | | SCAC4 |
| 1181 | UNLU | NAMMA CONTAINER LINES | | | SCAC4 |
| 1182 | UNLX | The Board of Regents of the University of Nebraska | added 10/2007 | | NAKINA |
| 1183 | UNLX | BOARD OF REGENTS OF THE UNIVERSITY OF NEBRASKA | | | PWRC |
| 1184 | UNLX | THE BOARD OF REGENTS OF THE UNIVERS | | | SCAC4 |
| 1185 | UNMA | UNICOM MANAGEMENT SERVICES | | | SCAC4 |
| 1186 | UNMC | UNCOMMON CARRIER INC | | | SCAC4 |
| 1187 | UNMD | UNIMODAL | | | SCAC4 |
| 1188 | UNME | U & ME TRANSFER INC | | | SCAC4 |
| 1189 | UNMI | UNITED MOTORS INC | | | SCAC4 |
| 1190 | UNMM | UNIVERSAL MACHINERY MOVERS | | | SCAC4 |
| 1191 | UNMT | UNKNOWN MEXICAN TRUCKING CARRIER | | | SCAC1 |
| 1192 | UNMT | UNITED MERCHANTS TRUCKING INC | | | SCAC4 |
| 1193 | UNNO | UNIVERSAL FIBERS | | | SCAC4 |
| 1194 | UNNT | UNION TRUCKING CO | | | SCAC4 |
| 1195 | UNOI | UNIVERSAL OIL INC | | | SCAC4 |
| 1196 | UNON | UNION DE EJIDOS DE PRODUCCION AGROP | | | SCAC4 |
| 1197 | UNOR | UNO TRANSPORTATION INC | | | SCAC4 |
| 1198 | UNOU | ALGECO NORWAY AS | | N | BIC |
| 1199 | UNOU | UNITEAM PISA | | | SCAC4 |
| 1200 | UNPC | UTI UNITED STATES INC | | | SCAC4 |
