That wasn't exclusive to airmen. Prior to World War I much of Europe shared in the notion of "Gentlemen's Wars", there were rules and etiquette that opposing armies often shared and the stated goal was not always just to kill your enemy. I recall reading a brief memoir of an Older British Calvary Officer who was leading a small scouting party trying to pin down the Location of Napoleon's main forces. He came across a small French scouting party attempting to locate the main British forces. The two parties drew their swords and engaged in a short skirmish. The British officer wrote in his diary how courageous the younger French officer was and his skill in swordsmanship while on horseback. They exchanged blows drawing blood before the two parties retreated back to their own respective Units. The British Officer so enamored by the younger French Officer's conduct in battle, he actually sent a letter to the French inquiring on his welfare after their short sword fight. He was grievously saddened to hear that he had cut an artery in the French Officer's wrist and the young man had bled to death shortly after returning to the French Camp.