What is indicated by a combination of an up and down arrow on the TCAS page?

A combination of an up and down arrow on the TCAS (Traffic Collision Avoidance System) page indicates that the target aircraft is climbing or descending. This visual cue is essential for pilots to quickly assess the vertical movement of nearby aircraft relative to their own. In TCAS displays, an upward arrow suggests that the target is climbing, while a downward arrow suggests a descent. When both arrows appear at the same time, it shows that there is active vertical movement happening, but the specific direction is not distinguished; rather, it confirms that the target is indeed changing altitude.

This information is critical for situational awareness and for pilots to make informed decisions in order to maintain safe separation from other aircraft. Understanding the TCAS indications is vital for effective navigation and collision avoidance in varying flight conditions.