Subchapter 9.4 – TCAS Resolution Advisory and Safety Alerts

Modern IFR aircraft are equipped with Traffic Collision Avoidance System (TCAS), which uses radar to detect nearby aircraft and generate warnings. TCAS operates independently of ATC and provides the last line of defense against mid-air collision.

TCAS has two levels of warnings:

Traffic Advisory (TA): TCAS detects an aircraft at some distance. The system says "Traffic, traffic," alerting you to look for the intruder. TA is informational; no maneuver is required. You remain under ATC control and should continue following ATC instructions while remaining vigilant.

Resolution Advisory (RA): TCAS calculates that another aircraft is on a collision course. The system commands an evasive maneuver, typically "Climb, climb" or "Descend, descend," with a vertical speed recommendation. RA is a direct command that overrides ATC instructions.