[GuerraCivil]

Silencing the rear gunner of bomber was a common practice in air war as it made it easier to shoot the enemy plane down - fighter pilots of all air forces did it and no one considered it to be "unethical". Comparing the rear gunner of a bomber with parachuted airmen the situation is different. Rear gunner is armed and can shoot back while parachuted pilot is (usually) unarmed and unable to do defend himself (there are some legends of pilots carrying pistols while parachuting and that they even shot planes down!).

Shooting the parachuted pilot is more complicated question. For what I know some German pilots like Galland and Gustav Rödel condemned strongly such practice as unethical. This of course did not stop some German pilots to do it. Maybe Galland and others like him wanted just to polish the image of Luftwaffe pilots for the time when war was over? Thus they created a myth of some "chivalry rules" in air war?

Probably there were some pilots in all air forces (incl. Japanese Navy/Army) who did not go after parachuted pilot in any case (even when he was parachuting over his own territory). It was also dangerous to focus on him if there were still active enemy fighters around.

In the Pacific war I do not know if Allied pilots shot parachuted Japanese pilots as often as Japanese shot Allied pilots. I have seen a gun camera clip in which P 51 pilot makes a pass on parachuted Japanese pilot. I do not know motifs, if it was a retaliation act vs. Japanese or a American practice of "aerial exterminating action" based on unwritten orders? The Japanese "aerial exterminating action" is better documented and many cases would have been unknown if after the war there had not been access to Japanese sources regarding this matter.