O: Oscar
O&D: Origin/Destination
O&D: Origins & Destinations
O-Level: Organization Level
O/C: Open Circuit
O/D: Origin/Destination
O/P: output
O/W: One way
O/W: One-Way
O/W: Overwater
O2: Oxygen
O7: OzJet
OADF: Overseas Aircraft Delivery Flight
OADU: Overseas Aircraft Delivery Unit
OAFTO: Orbiter Atmospheric Flight Test Office
OAHTS: orbiter avionics hardware tracking system
OALC: Ogden Air Logistics Center
OAMP: Optical Airborne Measurements Program
OAMP: Optical Aircraft Measurements Program
OANS: Observers Air Navigation School
OAP: Outside Air Pressure
OAPU: Overseas Aircraft Preparation Unit
OAR: Obusna Aeroplansva Radionica
OARS: Orbiter Avionics Radiation Specification
OAS: Orbiter Aeroflight Simulator
OAS: Orbiter Atmospheric Simulator
OAS: Orbiter Avionics Simulator
OAS: Orbiter Avionics System
OASCB: Orbiter Avionics Software Control Board
OASIS: Orbit Avionics Software Integration Study
OASM: Office of Aerospace Medicine
OAST: Office of Aeronautics and Space Technology
OAT: outside air temperature
OATL: Outside Air Temperature Limit
OATS: Officers Advanced Training School
OATS: Orbiter Avionics Tracking System
OBRM: On Board Replaceable Module
OBRM: On Board Replacement Module
obs: observation
OBS: observer