Volcanic ash is a menace to pilots since neither human eyes nor conventional radar can distinguish between volcanic ash clouds and those composed of water or ice. CSIRO Division of Atmospheric Research has developed AVADS - Airborne Volcanic Ash Detection System - a multi-channel infrared radiometer that utilises techniques and instrumentation based on satellite radiometers to discriminate between different types of clouds at distances of up to 100 kilometres. The system offers instant read-outs on the composition and movement of cloud formations and, because it is especially sensitive to the low concentrations of ash at the edges of clouds, allows pilots vital minutes in which to take evasive action.