It's time in the career of F/O Driscoll to progress from an Airco DH2 onto a Nieuport 17 against the Albatros D.IIs. At these crossover periods did British or German pilots fly in mixed plane flights as in new planes arriving to the front line squadrons a few at a time to replace the older planes. I think this is the way it would have happened but I'm happy to be corrected.