| 1 | OSA | Aero Astra | Callsign: Rostra, | MEX | AVCODES |
| 2 | OSA | Open Sky Aviation | | | ICAO1 |
| 3 | OSAA | OSARPA | | | SCAC4 |
| 4 | OSAAT | Osaka Airport Transortation | Subsidiary of Hankyu Corp. In 2022 merged into Hankyu Kanko Bus | J | TRAFFIC |
| 5 | OSAC | OMEGA SOLUTIONS TRANSPORT INC | | | SCAC4 |
| 6 | OSACB | Osaka City Bus Corporation | Owned by the Osaka Metro Company | J | TRAFFIC |
| 7 | OSAG | OSAGE OIL & TRANSPORTATION INC | | | SCAC3 |
| 8 | OSAG | OSPECA LOGISTICS MANAGEMENT TRANSPO | | | SCAC4 |
| 9 | OSAG | Osterwalder St. Gallen AG | | CH | TRAFFIC |
| 10 | OSAG | Osterwalder St. Gallen AG | | CH | VKM |
| 11 | OSAI | ORINOCO SHIPPING AGENCIES INC | | | SCAC3 |
| 12 | OSAKAB | Osaka Bus Co. | | J | TRAFFIC |
| 13 | OSAM | Osaka Monorail | | J | TRAFFIC |
| 14 | OSAP | OCEANA SHIPPING AG | | | SCAC4 |
| 15 | OSAR | OSAR TRUCKING CO, INC | | | SCAC3 |
| 16 | OSAW | OAKLEY SUB ASSEMBLY WINDSOR | | | SCAC4 |
