Next - Generation Airborne Collision Avoidance System

Building a collision avoidance system that can meet the safety standards required of commercial aviation is challenging. Lincoln Laboratory, in collaboration with other organizations, spent decades developing and refining the system that is in use today [1]. There are several reasons why creating a robust system is difficult. The sensors available to the system are imperfect and noisy, resulting in uncertainty in the current positions and velocities of the aircraft involved. Variability in pilot behavior and aircraft dynamics makes it difficult to predict where the aircraft will be in the future. Also, the system must balance multiple competing objectives, including both safety and operational considerations. Over the past few years, Lincoln Laboratory has been developing advanced algorithmic techniques for addressing these major challenges for collision avoidance. These techniques rely upon probabilistic models to represent the various sources of uncertainty and upon computer-based optimization to obtain the best possible collision avoidance system. Simulation studies with recorded radar data have confirmed that such an approach leads to a significant improvement to safety and operational performance [2]. The Federal Aviation Administration (FAA) has formed a team of organizations to mature the system, which has become known as Airborne Collision Avoidance System X (ACAS X). A satisfactory proof-of-concept flight test in 2013 will strengthen the goal of making ACAS X the next international standard for collision avoidance. In response to a series of midair collisions involving commercial airliners, Lincoln Laboratory was directed by the Federal Aviation Administration in the 1970s to participate in the development of an onboard collision avoidance system. In its current manifestation, the Traffic Alert and Collision Avoidance System is mandated worldwide on all large aircraft and has significantly improved the safety of air travel, but major changes to the airspace planned over the coming years will require substantial modification to the system. Recently, Lincoln Laboratory has been pioneering the development of a new approach to collision avoidance systems that completely rethinks how such systems are engineered, allowing the system to provide a higher degree of safety without interfering with normal, safe operations.