| Abbreviation | Definition |
|---|---|
| o/r | On Request |
| o/t | Other Times |
| O2 | Oxygen |
| OAA | Ohio Aviation Association |
| OAA | Oxford Aviation Academy |
| OAC | Ontario Aerospace Council |
| OACC | Oceanic Area Control Center |
| OAD | Optimal Aircraft Design |
| OAMP | Optical Aircraft Measurement Program |
| OAP | Odessa Aviation Plant |
| OAPU | Overseas Aircraft Preparation Unit |
| OAS | Office of Aviation Services |
| OAS | Office of Aviation Services's |
| OASES | Open Aviation Strategic Engineering System |
| OASUW | Objective Anti-Surface Warfare |
| OAT | Outside Air Temperature |
| OATS | Oxford Air Training School |
| OBEDS | Onboard Boeing Electronic Distribution System |
| obs | Observer |
| OBS | Omni Bearing Selector |