Traffic alert and collision avoidance system

Abstract

VOLUME 16, NUMBER 2, 2007 LINCOLN LABORATORY JOURNAL 277 tinuously on a jet transport aircraft in today’s environment could expect to survive more than 11,000 years of travel before becoming the victim of a mid-air collision. This accomplishment has only recently been realized. As shown in Figure 1, the number of hours flown annually by jet transport aircraft has more than quadrupled since 1970, but the rate of mid-air collisions over that period of time has dropped by an order of magnitude. The result is that today we can expect one mid-air collision every 100 million flight hours. Such an exceptional safety level was achieved through advances in air traffic surveillance technology and relentless attention to improving operational procedures. But as the September 2006 mid-air collision between a Boeing 737 and an Embraer Legacy 600 business jet over the Amazon jungle in Brazil demonstrates, maintaining safety is an ever present challenge. This challenge has been eased, but not eliminated, with the development and deployment of TCAS. TCAS is one component of a multi-layered defense against mid-air collisions. The structure of airspace and A collision between aircraft is one of the most sudden and catastrophic transportation accidents imaginable. These tragic events are rarely survivable—hundreds of people may die as the two aircraft are destroyed. In response to this threat, Lincoln Laboratory has been pursuing surveillance and alerting system technologies to protect aircraft operations both on the ground and in the air. Recent developments in the Runway Status Lights Program, for example, greatly reduce airport-surface collision risk due to runway incursions [1]. In the air, other systems have been developed and are currently in use to prevent midair collisions. This article focuses on the widely fielded, crucial technology called the Traffic Alert and Collision Avoidance System (TCAS). In the context of integrated sensing and decision support, TCAS illustrates the particular challenge of developing effective decision aids for use in emergency situations involving extreme time pressure. Despite the terrifying prospect of a mid-air collision, aviation travel is incredibly safe. A person who flew conThe Traffic Alert and Collision Avoidance System