O: Oscar
O-Level: Organization Level
O/C: Open Circuit
O/P: output
O/W: Overwater
OAFTO: Orbiter Atmospheric Flight Test Office
OAHTS: orbiter avionics hardware tracking system
OALC: Ogden Air Logistics Center
OAMP: Optical Aircraft Measurements Program
OAP: Outside Air Pressure
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: Orbiter Avionics Tracking System
OBRM: On Board Replaceable Module
OBRM: On Board Replacement Module
OBS: observer
OBS: Omni Bearing Select
obsv: observation
OBX: Obnoxious Cargo
OC: On Course
OCA: Obstacle Clearance Altitude
OCA: Oceanic Control Area
OCALC: Oklahoma City Air Logistics Center
OCCPNT: Occupant
OCNL: occasional
OCR: Optical Character Reading
OCS: Operational Control System
OE: Operating Experience
OEB: Operations Engineering Bulletin
OEM: Original Equipment Manufacturer
OEU: Operational Evaluation Unit