| 1 | OEC | Christophorus Flugrettungsverein | | | ICAO1 |
| 2 | OECC | OEC FREIGHT CHICAGO INC | | | SCAC4 |
| 3 | OECF | OEC FREIGHT WORLDWIDE CO LTD | | | SCAC4 |
| 4 | OECM | OEC (MTL) INC | | | SCAC4 |
| 5 | OECN | ONE FOUR EIGHT EIGHT ZERO SEVEN (14 | | | SCAC4 |
| 6 | OECO | OVERSEAS EXPORT CRATING CO INC | | | SCAC3 |
| 7 | OECP | OMEGA ENERGY CORP | | | SCAC4 |
| 8 | OECR | OPTRIM ENERGY CORPORATION | | | SCAC4 |
| 9 | OECX | Oldbury Electro-Chemical Co. | 7/1937-7/1954; 10/1957 (not listed); eliminated 10/1957 | | NAKINA |
| 10 | OECX | Oldbury Electro-Chemical Co. | 4/38-10/57; eliminated 10/57 | | NRHS |
| 11 | OECX | OLDBURY ELECTRO-CHEMICAL CO. | | | PWRC |
| 12 | OECY | OVERLAND ENTERPRISE CO | | | SCAC4 |
