Project Report ATC-371
Robust Airborne Collision Avoidance through Dynamic Programming
M.J. Kochenderfer
J.P. Chryssanthacopoulos
3 January 2011

Lincoln Laboratory
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
LEXINGTON, MASSACHUSETTS

Prepared for the Federal Aviation Administration,
Washington, D.C. 20591

This document is available to the public through
the National Technical Information Service,
Springfield, Virginia 22161

This document is disseminated under the sponsorship of the Department of Transportation, Federal Aviation Administration, in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof.
1. Report No.  2. Government Accession No.  3. Recipient's Catalog No. 
ATC-371 
4. Title and Subtitle  5. Report Date 3 January 2010

Robust Airborne Collision Avoidance through Dynamic Programming
6. Performing Organization Code
7. Author(s) 8. Performing Organization Report No.
Mykel J. Kochenderfer and James P. Chryssanthacopoulos ATC-371
9. Performing Organization Name and Address 10. Work Unit No. (TRAIS)
MIT Lincoln Laboratory 244 Wood Street
11. Contract or Grant No.
Lexington, MA 02420-9108 FA8721-05-C-0002
12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered
Department of Transportation Project Report Federal Aviation Administration 800 Independence Ave.,  S.W. 14. Sponsoring Agency Code Washington, DC 20591
15. Supplementary Notes
This report is based on studies performed at Lincoln Laboratory, a center for research operated by Massachusetts Institute of Technology, under Air Force Contract FA8721-05-C-0002.
16. Abstract
The Traffic Alert and Collision Avoidance System (TCAS) uses an on-board beacon radar to monitor the local air traffic and logic to determine when to alert pilots to potential conflict. The current TCAS logic was the result of many years of development and involved the careful engineering of many heuristic rules specified in pseudocode. Unfortunately, due to the complexity of the logic, it is difficult to revise the pseudocode to accommodate the evolution of the airspace and the introduction of new technologies and procedures. This report summarizes recent advances in computational techniques for automatically deriving the optimal logic with respect to a probabilistic model and a set of performance metrics. Simulations demonstrate how this new approach results in logic that significantly outperforms TCAS according to the standard safety and operational performance metrics.
This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
Unclassified Unclassified 116
FORM DOT F 1700.7 (8-72) Reproduction of completed page authorized

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EXECUTIVE SUMMARY

The Tra.c Alert and Collision Avoidance System (TCAS), currently mandated on all large trans-port aircraft, has been shown to signi.cantly reduce the risk of mid-air collision. TCAS uses an on-board radar to monitor the local air tra.c and logic to determine when to alert pilots to po-tential con.ict. If deemed necessary to prevent collision, TCAS will issue a resolution advisory to the pilots to climb or descend at a particular rate.
Developing robust collision avoidance logic that reliably prevents collision without excessive alerting is challenging due to sensor error and uncertainty in pilot response and, consequently, the future paths of the aircraft. The current TCAS logic was the result of many years of development and involved the careful engineering of many heuristic rules speci.ed in pseudocode. Unfortunately, due to the complexity of the logic, it is di.cult to revise to accommodate the evolution of the airspace and the introduction of new technologies and procedures.
　
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