Volcanic ash observation flights, 2010, 2011 and beyond

Arun K. Karwal, National Aerospace Laboratory NLR, Amsterdam, The Netherlands
Henk W. Jentink, National Aerospace Laboratory NLR, Amsterdam, The Netherlands

Abstract

In 2010 and 2011 aviation in Europe and over the Atlantic was severely affected by eruptions of the Eyafjallajökull and Grimsvötn volcanoes. Ash concentration thresholds were defined by authorities below which safe operations are possible. This approach requires flexi-ble use of airspace and continuously updated information from several sources to be integrat-ed and interpreted during an event. One of the sources used to gather information was (next to space- and ground-based measurements) airborne in-situ measurements of volcanic ash con-centrations.

NLR Flight Operations has been involved in such measurement flights in 2010 and 2011 us-ing a very basic sensor suite that was assembled in the hectic hours just before the flights. Nevertheless, valuable information was gathered on these flights that aided national decision making. Since then steps have been made to increase the capability of the measurement suite, optimize the operation of such flights, and complete the risk assessment for operations in vol-canic ash. On a European and even global scale several initiatives have been initiated to standardize in-situ measurement flights, drafting a recommended measurement sensor suite and addressing operational issues.

The paper will first of all explain the preparation and execution of the NLR volcanic ash ob-servation flights after the Eyafjallajökull and Grimsvötn eruptions. Secondly, sensor technol-ogy to measure volcanic ash will be explored. One observation is that the single most im-portant parameter in the decision making process, ash density (mass per unit of volume), can-not be measured directly. Finally, international developments will be discussed. Are we better prepared than 2 years ago?