Mechta, sorry loose wording on my part. I wasn't referring to Drone Wars UK; the "they" was referring to the various operators of UAVs. Many industrial concerns and national Air Forces have experimented with UAVs investigating technical and operational viability. The industry operators will only report mishaps when there is a regulatory imperative to do so. I suspect many Air Forces will only report mishaps only when the knowledge is already in the public domain. I'm aware of the odd mishap which doesn't appear in their listing hence the first part of my statement. The strict definition of 'safety' relates to the risk to life, not the economic losses accruing from a mishap. If you can operate within a sanitised range, you can achieve adequate safety as there is little or no risk to life. I'd hope this explains the second part of my statement.
I note that their database only starts in 2007. In the early 90s I attended the UAV Systems Conference in Bristol. The first Bristol conference was held in 1979. A lot of mishaps can occur in 28 years.
EAP