Computer Science Department
School of Computer Science, Carnegie Mellon University


A Formally Verified Hybrid System for the
Next-Generation Airborne Collision Avoidance System

Jean-Baptiste Jeannin, Khalil Ghorbal,
Yanni Kouskoulas*, Ryan Gardner*, Aurora Schmidt*,
Erik Zawadzi, André Platzer

October 2014


An abbreviated version of this report will appear in the
"Proceedings of Tools and Algorithms for the Construction and Analysis of Systems"
21st International Conference, TACAS 2015, 11-18 April 2015 (London, UK),
Christel Baier and Cesare Tinelli, Editors, LNCS. Springer 2015.

Keywords: Airborne Collision Avoidance, ACAS X, Hybrid Systems, Theorem Proving, Federal Aviation Administration, Aircraft, Markov Decision Processes, Cyber Physical Systems

The next-generation Airborne Collision Avoidance System (ACAS X) is intended to be installed on all large aircraft to give advice to pilots and prevent mid-air collisions with other aircraft. It is currently being developed by the Federal Aviation Administration (FAA). In this paper we determine the geometric configurations under which the advice given by ACAS X is safe under a precise set of assumptions and formally verify these configurations using hybrid systems theorem proving techniques. We conduct an initial examination of the current version of the real ACAS X system and discuss some cases where our safety theorem conflicts with the actual advisory given by that version, demonstrating how formal, hybrid approaches are helping ensure the safety of ACAS X. Our approach is general and could also be used to identify unsafe advice issued by other collision avoidance systems or confirm their safety.

28 pages

*The Johns Hopkins Applied Physics Laboratory, Laurel MD 20723

Return to: SCS Technical Report Collection
School of Computer Science

This page maintained by