| 2101 | OMDS | OMEGA DISTRIBUTION SERVICES INC | | | SCAC3 |
| 2102 | OME | Omega Air, S. de R.L. | | HN | AVCODES |
| 2103 | OME | Omega Aerial Refueling Services, Inc. | Callsign: Oemga Tanker, | USA | AVCODES |
| 2104 | OME | Ostmecklenburgische Eisenbahngesellschaft mbH | Neubrandenburg (Connex-Gruppe > Veolia Verkehr > OLA) | D | privat-bahn.de |
| 2105 | OME | Ostmecklenburgische Eisenbahn | | D | TRAFFIC |
| 2106 | OMEA | OMEGA ASSOCIATES LTD | | | SCAC3 |
| 2107 | OMEC | OMEGA TOOL CORP | | | SCAC4 |
| 2108 | OMEG | OMEGA TRAVEL INC | | | SCAC3 |
| 2109 | OMEI | OMEIR TRAVEL AGENCY | | | SCAC3 |
| 2110 | OMEP | OMNI ENTERPRISES INC | | | SCAC3 |
| 2111 | OMET | OKON METALS INCORPORATED | | | SCAC4 |
| 2112 | OMEU | ODOM MARITIME ENTERPRISES | | | SCAC3 |
| 2113 | OMF | Omniflys, S.A. de C.V. | Callsign: Omniflys, | MEX | AVCODES |
| 2114 | OMF | Omniflys | | | ICAO1 |
| 2115 | OMFB | OMNI FREIGHT BROKERS INC | | | SCAC3 |
| 2116 | OMFI | ONEIDA MOTOR FREIGHT INC | | | SCAC4 |
| 2117 | OMG | Aeromega Ltd. | Callsign: Omega, | GB | AVCODES |
| 2118 | OMG | Aeromega | | | ICAO1 |
| 2119 | OMGA | OMEGA PLANTATION | | | SCAC3 |
| 2120 | OMGB | ONESTOP MEDIA GROUP | | | SCAC4 |
| 2121 | OMGF | OMEGA FORWARDERS INC | | | SCAC3 |
| 2122 | OMGG | OMEGA TRUCKING INC | | | SCAC4 |
| 2123 | OMGI | OFFICE MAGIC INC | | | SCAC4 |
| 2124 | OMGL | OMEGA LEASING SERVICES INC | | | SCAC4 |
| 2125 | OMGM | OCEANSTAR MANAGEMENT INC | | | SCAC4 |
| 2126 | OMGT | OMEGA ALPHA TRANSPORT INC | | | SCAC3 |
| 2127 | OMHE | OSBORNES MOBILE HOMES | | | SCAC4 |
| 2128 | OMHL | OMAHAUL INC | | | SCAC3 |
| 2129 | OMHS | ORVILLES MOBILE HOME SERVICE INC | | | SCAC3 |
| 2130 | OMHU | ECONOMTRADE LLC | | RUS | BIC |
| 2131 | OMI | Omni Taxi Aereo S.A. | Callsign: Omni Air, | BR | AVCODES |
| 2132 | OMI | Omi Railroad Co., Ltd. | Subsidiary of the Seibu Railway Co. Ltd. | J | TRAFFIC |
| 2133 | OMIA | OIL MAN INC, THE | | | SCAC4 |
| 2134 | OMIC | OMI CORP | | | SCAC3 |
| 2135 | OMID | Ontario Midland R.R. Corp. | added 1/1980; 1/1980-7/2000; eliminated 4/2005; 7/2005 | | NAKINA |
| 2136 | OMID | Ontario Midland R.R. Corp. | added 1/80; 1/80-7/2000 | | NRHS |
| 2137 | OMID | ONTARIO MIDLAND RAILROAD CORP. | | | PWRC |
| 2138 | OMID | Ontario Midland Railroad | | | RSRV |
| 2139 | OMID | ONTARIO MIDLAND RAILROAD CORPORATIO | | | SCAC3 |
| 2140 | OMID | Ontario Midland Railroad Corporation | | CDN | TRAFFIC |
| 2141 | OMIE | OPEN MILE INC | | | SCAC4 |
| 2142 | OMIH | ORITT, MICHAEL | | | SCAC4 |
| 2143 | OMIL | OMI PETROLINK CORP | | | SCAC3 |
| 2144 | OMIL | OMI PETROLINK CORP | | | SCAC4 |
| 2145 | OMIQ | OCEANVIEW-MERCED-INGLESIDE TRUCKING | | | SCAC3 |
| 2146 | OMIQ | OMEGA MANAGEMENT INC | | | SCAC4 |
| 2147 | OMIR | OMI TRANSPORTATION INC | | | SCAC3 |
| 2148 | OMIR | OMI TRANSPORTATION INC | | | SCAC4 |
| 2149 | OMIS | OMNI SOURCE CORP | | | SCAC3 |
| 2150 | OMIS | OMNISOURCE TRANSPORT LLC | | | SCAC4 |
| 2151 | OMIT | O M I TRANSPORTATION SERVICES INC | | | SCAC3 |
| 2152 | OMJL | ONE MAN JOBS LLC | | | SCAC4 |
| 2153 | OMKE | OMEGA KAPPA ENTERPRISES INC | | | SCAC3 |
| 2154 | OMKE | OCEAN MARKER SPORT SURFACES LTD | | | SCAC4 |
| 2155 | OMKG | ODUM TRUCKING | | | SCAC4 |
| 2156 | OMKT | OSBORN MODEL KITS | | | SCAC4 |
| 2157 | OML | Organizacoes Mambra, Lda | Callsign: Manbra, | ANG | AVCODES |
| 2158 | OML | Organizacoes Mambra | | | ICAO1 |
| 2159 | OMLC | OMNI LOGISTICS CO | | | SCAC3 |
| 2160 | OMLD | OCEANLIFE MARINE LTD | | | SCAC3 |
| 2161 | OMLI | OMNI LINES INC | | | SCAC3 |
| 2162 | OMLI | OZARK MOUNTAIN LEASING INC | | | SCAC4 |
| 2163 | OMLL | OVERSEAS MARTINEZ LLC | | | SCAC4 |
| 2164 | OMLM | OML MARITIME CANADA INC | | | SCAC3 |
| 2165 | OMLM | OML MARITIME CANADA INC | | | SCAC4 |
| 2166 | OMLN | OMEGA LINES N V | | | SCAC3 |
| 2167 | OMLP | Ohio Midland Light & Power | 1/1975-1/1980 | | NAKINA |
| 2168 | OMLP | Ohio Midland Light & Power | 1/75-1/80 | | NRHS |
| 2169 | OMLP | OHIO MIDLAND LIGHT & POWER | | | PWRC |
| 2170 | OMLP | Ohio Midland Light and Power | | | RSRV |
| 2171 | OMLT | OMALLEY TRUCKING INC | | | SCAC3 |
| 2172 | OMLU | AXIS FERT TRADE DMCC | | UAE | BIC |
| 2173 | OMLX | OmniTRAX Leasing, Ltd. | 7/2000-7/2005 (not listed) | | NAKINA |
| 2174 | OMLX | OmniTRAX Leasing, Ltd. | Jul-00 | | NRHS |
| 2175 | OMLX | OMNITRAX LEASING LIMITED | | | PWRC |
| 2176 | OMLX | OmniTRAX Leasing | | | RSRV |
| 2177 | OMLX | OMNITRAX LEASING LTD | | | SCAC4 |
| 2178 | OMLX | OmniTRAX Leasing, Ltd. | | USA | TRAFFIC |
| 2179 | OMMA | ORTEGA MONROY, MAXIMINO | | | SCAC4 |
| 2180 | OMMC | OMNI MOVING CENTER | | | SCAC3 |
| 2181 | OMN | Sultan of Oman Air Force | Callsign: Majan, Designator OU recalled by IATA | OM | AVCODES |
| 2182 | OMN | Sultan of Oman Air Force | IATA: OU, Callsign: Oscar Uniform, ICAO callsign changed to Majan | OM | AVCODES |
| 2183 | OMN | Sultan of Oman Air Force | IATA: OU, Callsign: Majan, Designator OU recalled by IATA. ICAO callsign changed from Oscar Uniform | OM | AVCODES |
| 2184 | OMNB | OMNIBUS INC | | | SCAC3 |
| 2185 | OMNE | ORBIT MOVERS & ERECTORS INC | | | SCAC3 |
| 2186 | OMNF | OMNI FREIGHT SYSTEMS L L C | | | SCAC4 |
| 2187 | OMNG | OMNI LOGISTICS INC | | | SCAC4 |
| 2188 | OMNI | OMNI EXPRESS INC | | | SCAC3 |
| 2189 | OMNITECH | Omnitech Sp. z o. o | City: Gliwice | PL | TRAFFIC |
| 2190 | OMNL | OMNITAINER LINE INC. | | | SCAC3 |
| 2191 | OMNL | OMNITAINER LINE INC | | | SCAC4 |
| 2192 | OMNP | OMNI TRANSPORT | | | SCAC4 |
| 2193 | OMNQ | OMNI COURIER INC | | | SCAC4 |
| 2194 | OMNS | OMNISERVE SHIPPING COMPANY LIMITED | | | SCAC3 |
| 2195 | OMNT | OMNI TRANSPORT INC | | | SCAC3 |
| 2196 | OMNU | AIR LIQUID ITALIA SERVICE SRL | | I | BIC |
| 2197 | OMNU | OMNIATRANSIT S R L LOGISTICA LIQUID | | | SCAC4 |
| 2198 | OMNW | OMNI TOOL LTD | | | SCAC4 |
| 2199 | OMNX | OmniSource Corp. | added 7/2006 | | NAKINA |
| 2200 | OMNX | OMNISOURCE CORP. | | | PWRC |
