There is a need for a real-time volcanic ash advisory system for aviation which could provide improved accuracy and timeliness in warnings to planes in flight as well as to air traffic controllers for flight planning. To provide an operationally useful capability at reasonable cost, it is essential that the system elements take maximum advantage of the weather sensing and information dissemination system under development by the FAA and NWS. Volcanic ash should be treated as a type of weather hazard similar to regions of icing and thunderstorms. Real-time information from ground sensors, unmanned air vehicles, air carriers, and satellites would be used to estimate current and predicted ash systems to pilots in flight, ATC controllers, traffic management units and airlines. Future research should focus on defining the ash densities and time exposures of concern to aircraft, resolving the sensor mix for measuring the ash density and extent, and validating models for ash transport.