Exploration of new algorithms for airborne collision detection and avoidance to meet NextGen capabilities

Abstract

As the aviation community moves toward the Next Generation Air Transportation System (NextGen), current airborne collision avoidance technology may become inadequate. The Traffic Alert and Collision Avoidance System (TCAS) was developed some time ago, and its ability to accommodate the air-to-air applications and Air Traffic Control (ATC) procedures that are envisioned for NextGen is limited. There is a need to analyze the role of future NextGen technologies such as Automatic Dependent SurveillanceBroadcast (ADS-B) in the overall collision avoidance concept and architecture. This paper will describe a MITRE research effort addressing the following three fundamental research questions: What are the desired NextGen operations that are incompatible with current TCAS? What new enabling technologies and design principles could meet the NextGen needs? What are the key functional needs that ensure enhancements and modifications do not detract from safety-the primary function of the collision avoidance system? In this paper we will discuss the technical approach applied to the research, and identify projected TCAS limitations in meeting future air-toair applications and ATC procedures.

Design principles and algorithm development for two types of NextGen airborne conflict detection and collision avoidance

“…Otherwise, the choice of estimation filter for v (ownship or intruder) depends on the size of Q. The remainder of the method is identical to the current TCAS logic [9]. Altitude with 25-foot Q is estimated with an alpha/beta filter that chooses amongst four sets of coefficients {(α 1 ,β 1 ),(α 2 ,β 2 ),(α 3 ,β 3 ),(α 4 ,β 4 )}.…”

“…To determine this, the baseline TCAS performance must be established as a reference for evaluation. The RTCA TCAS Minimum Operational Performance Standards (MOPS) [9] specified the algorithms for the manufacturers' implementation, but did not provide performance specifications or performance thresholds. Instead, a safety study of TCAS II [10] was performed and showed that TCAS II reduced the risk of near mid-air collision (NMAC).…”

Future airborne collision avoidance — Design principles, analysis plan and algorithm development

“…We also explored potential incompatibilities between the current TCAS II design and new proposed operational procedures and airborne applications [8]. We then explored a range of options for future CASs to accommodate incompatibilities that may arise and focused our research on recasting the CAS with new algorithms and enhanced surveillance sources such as ADS-B.…”

“…Within these three alternatives, our initial research focus is the passive ADS-B based CAS. We identified key issues with the passive approach that require investigation [8].…”

“…In an earlier phase of this work, we identified three major areas of needed capability improvements for the NextGen collision avoidance system (NextCAS) [8].…”