TCAS stands for?

• A. Traffic Collision Avoidance System
• B. Traffic Alert Collision Avoidance System
• C. Terrain and Collision Alert System
• D. Traffic En Route Control System

Answer: (A)

Traffic Collision Avoidance System is the correct expansion. This onboard system monitors nearby traffic by exchanging transponder signals and then calculates if a collision risk exists. If a risk is detected, it provides advisories to help the pilot avoid the threat, including Traffic Advisories and, when needed, Resolution Advisories to change altitude or maneuver to stay clear. The other options mix in terms from other systems or use a wording that isn’t the official name—Terrain Awareness and Warning System is a separate terrain-related system, and there isn’t a system officially named Traffic Alert Collision Avoidance System. The official name is simply Traffic Collision Avoidance System.