Collision Avoidance Systems, airplanes

Airplane navigation in open space is always performed under the risk of collision. Mid-air collision and ground proximity are the most hazardous threats. Each modern airplane is equipped with Traffic alert and Collision Avoidance System (TCAS) and Terrain Awareness and Warning System (TAWS) to predict dangerous collision and provide a pilot a set of recommendations for conflict resolution. TCAS is grounded on secondary surveillance observation and estimation of time to fly to the closest point of approach. TAWS is only a computation system on board, that uses multiple sensors data (such as Global Navigation Satellite System) to detect a potential collision with terrain.