| 1 | ONA | Yeongnam Air Co. Ltd. | IATA: OE, Callsign: Yeongnam Air, Founded in 2008. Commenced operations on 25 July 2008. Ceased operations in December 2008. | ROK | AVCODES |
| 2 | ONAI | ONALA TRUCKING CORP | | | SCAC4 |
| 3 | ONAL | O'NEAL, TOLAN TRANSPORTATION & LOGI | | | SCAC3 |
| 4 | ONAN | ONE FOUR FOUR FIVE NINE ONE THREE ( | | | SCAC4 |
| 5 | ONAV | OCEANIC NAVIGATION CORPORATION | | | SCAC3 |