Yes. They're an Ace too. Bomber gunners and back seaters have been credited as Aces if they are responsible for the kills, while the pilot is not. There's really no set rules for what a Flying Ace is, outside of knocking 5 aircraft out of commission, it's just up to the country and what they want to consider a kill. The US has historically counted aircraft on the ground as kills towards the achievement, not sure if we still do though.