ACAS X replaces TCAS II's fixed logic tables with probabilistic optimization, reducing nuisance alerts and enabling collision avoidance for unmanned aircraft in shared airspace.
The 2002 Überlingen mid-air collision killed 71 people after a crew overrode their TCAS Resolution Advisory - a case study in why RA compliance is an absolute rule.
ACAS X replaces TCAS II's 1990s-era lookup table with a real-time dynamic programming algorithm designed for drones, eVTOLs, and modern mixed airspace.