In response to the rare but serious threat that volcanoes pose to airplanes, the Federal Aviation Administration and the National Oceanic and Atmospheric Administration recently established a volcano monitoring service. Under the agreement NOAA will contact FAA if satellite images show ash eruptions reaching higher than 5 km along flight routes.The volcano monitoring service will also depend on pilots, the U.S. Geological Survey, and the Smithsonian Institution's Scientific Event Alert Network for reports of volcanic eruptions.