This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
TA
Traffic Advisory
A Traffic Advisory is the first level of alert generated by the Traffic Collision Avoidance System (TCAS). A TA is issued when TCAS calculates that another transponder-equipped aircraft is approaching and may constitute a threat, but the projected closest point of approach is still far enough away that a manoeuvre is not yet required. The TA serves as a warning to the crew to look outside, check the Navigation Display (ND) for the intruder’s position, and prepare to respond if the situation escalates. A TA does not require any deviation from the current flight path.
On the ND or TCAS display, the conflicting traffic is shown as a filled amber circle at the position and relative altitude where it is detected. An aural alert - “Traffic, Traffic” - accompanies the visual indication. TAs are typically generated 35-48 seconds before the projected closest point of approach, giving crews time to identify the traffic visually or via ATC. If the geometry worsens, TCAS will upgrade the TA to a Resolution Advisory (RA), at which point the crew must manoeuvre as directed. The TA phase is a heads-up period designed to improve crew situational awareness before any evasive action becomes necessary.