When is it safe to fly a plane through volcanic ash?

Data on particle size, shape, and terminal velocities of volcanic ash particles are required to understand how the irregularly-shaped grains are likely to affect both aircraft and public health. Being able to make this kind of statement makes it easy for me to get up in the mornings! It is always nice to know your work can genuinely influence the wider world. With the current eruption in Indonesia volcanic ash is again a hot issue.

In April and May 2010, large areas of European airspace were closed due to the eruption of the Icelandic volcano, Eyjafjallajökull. Although this latest event appeared to catch the world by surprise, and there is clearly still a great deal to learn, vulcanologists, geologists and mineralogists are already hot on the trail of effective technological and methodological solutions.

 Volcanic Ash: To fly or not to fly? – New report published 

In response to Eyjafjallajökull, the Institution of Mechanical Engineers  [IME] published a report in October entitled; ‘Volcanic Ash: To fly or not to fly?’. In this review they call for “significant investment and action” towards the establishment of clear procedures for assessing whether or not it is safe to fly following a volcanic eruption based on extensive modelling. In their final recommendations they stress the need for model data to be based on “measurements of actual volcanic eruptions for their particle size, chemistry and ash volume together with improved modelling of the subsequent atmospheric dispersion over distance and time.”

Obviously, modelling is better than real practical experiments in this case, as nobody wants to be on a flight that experiences engine issues due to ash, as passengers on a BA flight in Indonesia in 1982 and a KLM flight in Alaska in 1989 will testify!

Several published studies have demonstrated that the Mastersizer 2000 particle size analyzer from Malvern Instruments is an ideal tool to gather data to help assess potential outcomes of ash distribution following a volcanic eruption. So perhaps it’s a leap for me to claim to be helping to influencing world events but just knowing that the work we do at Malvern might directly influence whether or not I can fly my family to somewhere hot next summer without fear of getting stuck there for months is satisfying enough.

Laser diffraction is ideal for volcanic ash analysis

You don’t have to take my word for it of course.

In 2003 Riley et al, from Michigan Technological University used laser diffraction to measure grain-size distributions of bulk samples in a method that uses quantitative shape measurements of distal volcanic ash with particles less than 200 mm in size to expand our understanding of volcanic ash transport and remote sensing measurements of volcanic clouds. (J. Geophys. Res., 108, 2504)

In 2004, a study from Sperazza et al. from the University of Montana showed that laser diffraction can rapidly and precisely measure sediment as fine as 10 µm without the need for extensive mineralogical determinations (High-Resolution Particle Size Analysis of Naturally Occurring Very Fine-Grained Sediment Through Laser Diffractometry).

Then, in 2007 Claire J. Horwell from the University of Durham used grain-size analysis of volcanic ash for the rapid assessment of respiratory health hazard. (J. Environ. Monit., 2007, 9, 1107 – 1115)

 Volcanic Ash & Eyjafjallajokull: the fall out

The ongoing consequences of the Eyjafjallajokull eruption and subsequent volcanic ash are still being calculated.

According the IME report:

  • 33 nations grounded over 100,000 flights
  • 5,000,000 travellers were stranded around the world
  • This disruption is estimated to have cost the European economy between €1.5–2.5bn

The real cost of delayed or uncertain data and analyses following this type of natural disaster are very clear. Additionally, while the ash cloud from the Icelandic eruption remained high enough from the ground to pose no threat, volcanic ash can have the potential to cause acute and chronic respiratory diseases if the particles are sufficiently fine to enter the respiratory system. Accurate information enabling fast decisions can save millions while ensuring the highest levels of safety are maintained.


High-Resolution Particle Size Analysis of Naturally Occurring Very Fine-Grained Sediment Through Laser Diffractometry
Michael Sperazza; Johnnie N. Moore; Marc S. Hendrix
Journal of Sedimentary Research (1 September 2004) 74 (5): 736–743.
DOI: 10.1306/031104740736