Tool for Computing Unmitigated Collision Risk Using Traffic Density Data

Overview
This software is intended to process observed aircraft traffic information into unmitigated collision rates given user-specified geographic regions or aircraft tracks. The user may also specify the time of day, month of year, and day of week to be evaluated. Unmitigated collision rates are useful for aircraft safety assessments and may be combined with the efficacy of mitigations—e.g., air traffic control, detect and avoid, see and avoid—in order to estimate the total operation safety.

The traffic density data are extracted from raw air traffic and air defense radar data provided by the Air Force 84th Radar Evaluation Squadron. More than 300 long-range and short-range radars were used to generate the traffic data; the radar data are tracked and fused to ensure that traffic data are not duplicated (see Appendix F of this document for additional detail regarding this process). The fused data are then aggregated by temporally and spatially discretizing the traffic data. For each temporal and spatial cell, the total aircraft flight time and maximum instantaneous occupancy are captured; this software then estimates the traffic density and then the collision risk. The data files are provided separately on Zenodo.

Although it is expected that collision rates are of primary interest, other event rates can be estimated given user-specified input parameters. An event is when another aircraft comes within the user-specified volume, and the event rate is the estimated average number of events per flight hour. For example, the event rate of near-mid-air collisions (NMACs), typically defined as a loss of separation 500 ft horizontally and 100 ft vertically, may also be of interest.