Weather prediction for airborne separation assistance systems

The concept of airborne separation assistance systems (ASAS) is receiving increasing interest as a future capability for the management and control of air traffic. ASAS systems make use of flight crews to provide some or all of their own protection in maintaining safe distances with other aircraft, restricted regions of airspace, and potentially unsafe convective weather. Concepts for use of ASAS range from increasing situational awareness to enabling full autonomy of operation from air traffic controllers. Most proposed concepts rely on on-board avionics to detect a potential loss of separation with other aircraft or regions of airspace. Some concepts also rely on airborne systems to resolve these conflicts. These functions are referred to as airborne conflict detection and resolution (CD&R). Another function under exploration requires an aircraft to perform time or distance spacing relative to another aircraft. This paper presents an overview of the current state of ASAS research and development. It also describes how predictions of winds aloft and convective weather are used by prototype CD&R and spacing functions in simulation and initial flight trials. The paper discusses issues facing the developer of airborne CD&R and spacing technology, including sensitivity of winds-aloft predictions to conflict detection, the handling of dynamic convective weather, and capabilities of modern aircraft to comply with planned four-dimensional trajectories in the presence of wind prediction errors.