Fairly early on in the conflict Scharff was asked to find out the meaning of a long string of tracer rounds fired from the machine guns of an allied fighter pilot. Eventually he was able to trick a loose lipped captive into letting him know that the string of tracers was an indicator that the ammo belt had come to it's end.
Scharff passed this information up the chain believing that he had discovered information which would enhance the Luftwaffe's ability to take out enemy pilots as the defenseless belligerents should be easy pickings once their condition was known. He was mistaken about this, he later learned Luftwaffe officers had taken the knowledge to mean that attacking the disarmed aircraft was unsporting, it didn't appeal to their sense of old world chivalry to vanquish them, so the unarmed allied pilots were just given a friendly wave goodbye and allowed to fly home unmolested. Many Luftwaffe officers were also aware of the Geneva Conventions' Rule 47 which bars attacks against 'Persons Hors de Combat'. Scharff expressed some dismay over this in his autobiography, knowing that letting enemies fly home to fight another day wasn't helping Germany in the big picture.
Meanwhile the allies had no misgivings about violating the Geneva Conventions, they didn't even educate their officers on the limitations the treaties presented.
Hans Scharff later ended up working as an artist for Walt Disney and the FBI has adopted the interrogation methods Scharff developed.
