| Acronym | Meaning |
| APCS | Automated Project Control System - ARTEMIS |
| APID | Applications Process Identification |
| APS | Acquisition Processor Subsystem |
| ARC | Aggregation Of Red Cells |
| ARC | Ames Research Center |
| ARS | Archive And Retrieval Subsystem (PPCU) |
| ARTEMIS | Project Management Software System - Metier Product |
| ARTS | Automated Resource Tracking System - ARTEMIS |
| ASCII | American Standard Code For Information Interchange |
| ASE | Airborne Support Equipment |
| ASP | Attitude Sensor Package |
| ASRS | Automated Support Requirements System |
| ASSY | Assembly |
| AST | Astro Star Tracker |
| ASTER | Advanced Spaceborne Thermal Emission And Reflection Radiometer |
| ASTG | Aerospace Test Group |
| ATC | Absolute Time Command |
| ATCS | Active Thermal Control System |
| ATE | Automated Test Equipment |
| ATLAS | Atmospheric Laboratory For Applications And Science |
| ATMOS | Atmospheric Trace Molecule Spectroscopy |
| ATP | Accelerated Training Program |
| ATP | Acceptace Test Procedure |
| AWAD | Assembly Work Authorization Document |
| B | Bit |
| B&P | Budgetary And Planning |
| B&W | Black And White |
| B-1 | DIV B-1 Division (Rockwell) |
| B/A | Bank Angle |
| B/A | Barometric Altimeter |
| B/A | Buffer Amplifier |
| B/C | Bench Check |
| B/L | Baseline |
| B/O | Booster Orbiter |
| B/O | Breakout |
| B/O | Burnout |
| B/SC | Brake Skid Control |
| B/SEC | Bits Per Second |
| B/SMPL | Bits Per Sample |
| B/U | Backup |
| B/V | Bleed Valve |
| B/W | Black And White |
| BA | Bank Angle |
| BA | Breathing Air |
| BAC | Boeing Aircraft Company |
| BAC | Booster Assembly Contractor |
| BAC | Buffer Access Card |
| BACS | Body Axis Coordinate System |
| BAI | Barometric Altitude Indicator |
| BAIR | Breathing Air |