Design, implementation and evaluation of a system to support Well Clear

Both from an operational and from a design perspective there is a need for an objective, quantitative definition of “well clear”. The Sense and Avoid Science and Research Panel (SARP[3]) considered three concepts for the definition of well-clear. All concepts use a spatial threshold as part of the criterion. A so-called Velocity Scaled Protection Volume (VSPV) concept, additionally uses a time constant to compute two separate spatial thresholds: One based on ownship velocity and one based on intruder velocity. The other concepts use a temporal threshold based on the relative velocity between ownship and intruder. The quantitative definition was tuned to yield a 1.5% probability of an NMAC in case of an unmitigated well clear violation. In August 2014, the SARP recommended a quantitative definition of well clear to RTCA SC-228. To aid the pilot in remaining well clear, several concepts for the conflict prediction and resolution function are being pursued. These concepts differ in the design of the graphical user-interface but also in the level of automation (LOA) applied for Decision Selection. With a LOA of 2, the conflict prediction function offers a complete set of decision/action alternatives. An example of a concept in which this LOA is used is the conflict probe display. The conflict prediction function uses the well clear definition to compute whether and if so where a well clear violation is predicted to occur for a specified range of manoeuvre options, and presents the resulting conflict space to the pilot. Every manoeuvre that is predicted to avoid the conflict space is a potential option to remain well clear. Based on this and other information, the pilot can select a manoeuvre. In case the LOA of the function is increased to 4, the system will only present a single manoeuvre option to the pilot. This is more comparable to a Traffic alert and Collision Avoidance System (TCAS) Resolution Advisory (RA). Two designs of a conflict probe display have been realized as extensions to a CDTI. With both systems, the algorithms that define the well clear boundary and the spatial and temporal thresholds can be manipulated. The implementations have been used in a range of evaluations, both in simulation and actual flight test. The full paper will discuss the design aspects and decisions, the implementation and results in more detail. [1] For the purposes of this work, “Sense and Avoid” and “Detect and Avoid” are two terms referring to the same functionality. [2] For the purposes of this work, “Traffic Avoidance” and “Self Separation” are two terms referring to the same capability. [3] The SARP is a U.S. government funded organization designed to bring together SAA community stakeholders to close known research gaps.