Airborne Volcanic Ash - A Global Threat to Aviation

http://pubs.usgs.gov/fs/2010/3116/

Explains the problem, describes procedures used to cope with it, ways of monitoring and detecting hazardous conditions, and warning systems currently available to help mitigate the dangers.

by Neal, Christina A. and Guffanti, Marianne C.

U.S. Geological Survey Fact Sheet 2010-3116

This publication is available only as a PDF document.