Volcanic cloud monitoring issues at the Darwin VAAC

We discuss recent eruptions from Ruang, Semeru and Rabaul, and some mysterious aircraft encounters over Micronesia, in the context of current Darwin VAAC operations. Ruang was generally monitored successfully, with some qualifications such as a high level, eastward moving SO2 cloud that was only clear in post-analysis, and the complete lack of aviation 'SIGMETs'. Rabaul and Semeru are both long running, generally low level eruptions where little can be seen on satellite imagery. Three aircraft encounters occurred over Micronesia without the source of the volcanic cloud being identified. While International Airways Volcano Watch performance is steadily improving, there are still significant scientific and procedural concerns highlighted by the above cases.