First International Symposium on Volcanic Ash and Aviation Safety: Program and Abstracts [open pdf - 8MB]
"Between December 1989 and February 1990, five commercial jetliners suffered damage from encounters with volcanic ash from Redoubt Volcano. [...] One outcome of the Redoubt incidents has been to increase interest in the issue of volcanic hazards and aviation safety among a broad group which includes commercial and military air operators, aircraft manufacturers, the Federal Aviation Administration, the National Weather Service, and the U.S. Geological Survey. To focus this interest, the First International Symposium on Volcanic Ash and Aviation Safety is being held in Seattle, Washington in July 1991. The AIMS of the symposium are: 1. to encourage improvements in the detection, tracking, and warning of volcanic ash hazard so that aircraft may avoid ash clouds; and 2. to review the effects of volcanic ash on aircraft so that pilots who encounter ash can respond appropriately."
U.S. Geological Survey: https://pubs.usgs.gov/
First International Symposium on Volcanic Ash and Aviation Safety. Seattle, Washington. July 8-12, 1991