Traffic Alert Collision Avoidance System is a system on aircraft that prevent the mid air collision more affectively. Nearly all qircraft in world are equipped with this system and it is important to know what these warnings from systems mean and how to properly react from it.

A bit old aircraft, like DC-9 and MD-80 will have saparate TCAS screen and most of the modern aircrafts have TCAS on navigation panel.

TCAS display on modern jets


TCAS display on MD-80 at lower right side.

Types of Alerts

Traffic Advisory (TA)

  1. sounds when another traffic gets close.
  2. sound once and reset for further TA.
  3. pilot should closely monitor radar and outside window if this occurs.

Resolution Alert (RA)

  1. System will shout either climb or decend.
  2. pilots should always follow decision of TCAS when RA occurs even if it contradics with ATC's direction.
  3. Quickly disengage autopilot and to climb, or decend to displayed pitch.
  4. In case of increase climb or jncrease decend alert come out, follow it.
  5. When it alerts eithe climb now or decend now, change your original direction and follow new direction.
  6. Maintain Vertical Speed or Monitor Vertical Speed both occur when the obstacle goes out of RA pitch commending range. It means to keep watch out and keep pitch atitude away from the red area.

Clear of Conflict

   - the obstacle is no longer a danger, and RA is no longer affective.

Other traffics on radar are either proximate traffic or other traffic, which are not likely to cause TA or RA.

The arrow next to diamond(represent traffic) are the direction of traffic and their rate of climbing or decending.

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