The growing frequency of launches and re-entries of space vehicles has increased impact on other users of the National Airspace. Because these activities have a relatively high probability of failure, the FAA closes airspace proactively to mitigate the potential impact of debris resulting from a breakup event. The FAA Office of NextGen and Office of Commercial Space Transportation have been working to develop a systematic solution to reduce the spatial and temporal extent of airspace closures. A key element of the solution is developing the capability to respond in real-time to a failure. This requires data communication between the space vehicle and the FAA, procedures to communicate air traffic direction to pilots, and software to compute the real-time determination of the hazarded area. A key objective is to maximize the time allotted for aircraft to fly out of the hazarded region.

We have developed models, algorithms, and prototype software to compute four-dimensional aircraft hazard volumes within seconds following a presumed space vehicle failure. This process accounts for many physical processes, including the behavior of an intact vehicle from the last available state, breakup dynamics, fall of debris, the vulnerability of aircraft. The method characterizes uncertainty in each of these processes (also given that only limited information may be available in real-time).  The resulting volume must be optimized to be small enough such that there is time for aircraft to exit it, but large enough to sufficiently mitigate the risk to aircraft. The approach is based on significant experience with probabilistic modeling of the hazards to aircraft, combined with testing numerous potential failure scenarios of launch and re-entry vehicles.