Well Clear: Conflict Prediction and Alerting in the Terminal Environment

The current Minimum Operational Performance Standards (MOPS) for Detect and Avoid systems in the US are for aircraft transitioning to and from Class A or special use airspace, traversing Class D, E, and G airspace. Current standardization activities are evaluating how to expand the MOPS to include the terminal area as well as Class C and B airspace. A key concept for the MOPS is the hazard space, which is quantified using the Well Clear definition. For effective alerting and guidance in the terminal area the size of the hazard space must be reevaluated. This paper discusses two adjustments to the hazard zone definition that improve the alerting and guidance performance of DAA systems in the terminal environment. The first enhancement is intended to provide the pilot with improved information on the expected impact of intruders turning onto baseleg. The second enhancement is intended to prevent the DAA system from providing horizontal guidance that results in a loss of separation with terrain. The proposed enhancements require the addition of an airport database with runway threshold coordinates and a digital terrain elevation database. To evaluate integration aspects and expected performance, both enhancements have been added to CPDS, a DAA display, guidance and alerting system. Simulation has been used to test the resulting implementation and evaluate different configurations. Further analysis and evaluation is required to substantiate a more refined selection of the values for these key design parameters.