In a new article published in Nature, the team behind the «Airborne Volcanic Object Imaging Detector – AVOID» system report the results of an experiment conducted over the Atlantic Ocean. It confirmed the ability of the device to detect and quantify volcanic ash in an artificial ash cloud.
Airborne volcanic ash particles are a known hazard to aviation. As the particles are too fine for both the naked eye and on-board radar detection, there are no means available today to detect ash in flight for commercial aviation.
Keeps the airspace open
Still, as the 2010 Icelandic eruption of Eyjafjallajökull demonstrated, the economic cost and societal impact of such volcanic activity is high enough to make finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings worthwhile.
Dr. Fred Prata of Nicarnica Aviation, a spin off from NILU, has designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial aircraft at distances of more than 50 km ahead. Such warning gives sufficient time to change a plane’s course and avoid the ash cloud.
1000 kilos of ash in the atmosphere
The final test of the camera was set up to take place over the Bay of Biscay in March 2013.
– We used three different aircraft for the experiment, explains PhD candidate Andreas Vogel at NILU’s department of Atmosphere and Climate. – The main aircraft carrying and releasing 1000 kilos of ash was an AIRBUS A400M flight-test aircraft, followed by a Diamond Airborne Sensing aircraft (DA42-MPP) with an optical particle counter mounted on its nose. This is the aircraft I was in, and our mission was to obtain verification of the AVOID measurements by flying inside the ash cloud and make in situ measurements of ash particulates.
After the ash was released from the main aircraft, it formed an ash cloud approximately 2 km wide and 12 km long. Within 30 minutes of the ash cloud layer forming the third aircraft, an A340 carrying the AVOID instrument, flew towards it from approximately 80 km distance at an altitude of 15,000 ft. The aircraft turned at approximately 20 km from the location of the ash layer. Three further approaches in different altitudes were made toward the ash layer, to image the ash from above, along the limb and from below.
The experiment was done to prove that the AVOID system is capable to detect volcanic ash under controlled conditions and to validate the camera sensors with in-situ instruments explains Vogel. – What we found was that in situ measurements and the AVOID measurements correlated very well; they indicated the same amount of ash as well as the same altitude range in the atmosphere. In other words, our remote detection of volcanic ash from a long-range flight test aircraft is a success.