Aircraft frequently encounter volcanic ash when airborne. In the aftermath of these encounters, virtually the entire fuselage of an aircraft can be contaminated with ash, necessitating a thorough cleaning of the cockpit, instrument panel, circuit breaker panels, passenger and baggage compartments. The electrical and avionics units can be so heavily contaminated that complete replacement is necessary, mainly due to the possibility that all the units could have suffered from overheating. The ash also contaminates the cargo-hold fire-warning system and can generate nuisance fire warnings which are due to the volcanic ash in the air rather than smoke from a fire.The present proposal aims to provide an advanced airborne volcanic ash detection apparatus which will make use of special machine vision interrogation of volcanic ash (tephra) and novel image analysis software. The integrated retrofittable system will examine air in the aircraft’s ventilation ducts. By interrogating foreign bodies in the fresh air entering the cabin and identifying the type, size and number of particles per unit time and inferring the presence of low level ash particles in the possible presence of other solids in the air e.g. sand etc an early warning may be conveyed to the crew whence appropriate action may be taken to reduce the exposure of the aircraft, thus making possible enormous savings on maintenance costs.