Fullofit, I thought it very odd as well that an Aviatik would initiate an attack. I do have a possible theory though. As Swany and his G/O were gliding down towards the mud there was a go-round in progress quite some distance above them that looked to be between a pair of Aviatiks and several Nieups. Perhaps one of the German planes in that fight dropped down as an evasive maneuver and suddenly found itself next to yet another hostile plane. Whatever the reason, to Swany and Craig it still appeared as a dreaded Spectre.