 Complete the following phrase:  As Dickson had predicted, initially air combat was extremely rare, and definitely subordinate to reconnaissance. There are even stories of the crew of rival reconnaissance aircraft exchanging nothing more belligerent than smiles and waves. This soon progressed to throwing grenades, and other objects  even grappling hooks. The first aircraft brought down by another was an Austrian reconnaissance aircraft rammed on 8 September 1914 by Russian pilot Pyotr Nesterov in 