Active Thermal Control System
Active Thermal Control Systems
Active Thermal Control Subsystem
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Audit Tracking and Control System
Air Traffic Control Section
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Access Tandem Codes
Advanced Tactical Communications Syste…
Advanced Timed Channel Selection
Advanced Train Control System
Advanced Train Control Systems
Air Traffic Communications Station
Air Traffic Control Squadron
air traffic controllers
Air-Traffic Control Service
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Authorized Training Centers
Automated Train Control System