Technology preventing vehicles from crashing.

An airborne collision avoidance system (ACAS, usually pronounced as ay-kas) operates independently of ground-based equipment and air traffic control in warning pilots of the presence of other aircraft that may present a threat of collision.

A traffic alert and collision avoidance system (TCAS, pronounced ; TEE-kas) is an aircraft collision avoidance system designed to reduce the incidence of mid-air collision between aircraft.

Carrier-sense multiple access with collision avoidance in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle".