One of those times when Wiki is quite interesting: http://en.wikipedia.org/wiki/Attacks_on_parachutists As ever, it's a Curate's Egg of a page, but it contains nuggets: However, the Hague Rules of Air Warfare never came into force, and despite the strong feelings of chivalry around this issue, there was no legal prohibition on targeting defenseless airmen before or during the Second World War. In 1949, as a result of widespread practices and abuses committed during the Second World War, the newly modified and updated versions of the Geneva Conventions came into force providing greater protections to protected persons but there was still no explicit prohibition on the shooting of parachuting enemy pilots. However, despite this, military manuals around the world contained prohibition on attacking enemy pilots parachuting from an aircraft in distress. Paragraph 30 of the U.S. Army's Field Manual published by the Department of the Army, on July 18, 1956 (last modified on July 15, 1976), under the title "The Law of Land Warfare", states: 30. Persons Descending by Parachute The law of war does not prohibit firing upon paratroops or other persons who are or appear to be bound upon hostile missions while such persons are descending by parachute. Persons other than those mentioned in the preceding sentence who are descending by parachute from disabled aircraft may not be fired upon. In 1977, this practice was finally codified in Protocol I in addition to the 1949 Geneva Conventions: Article 42 - Occupants of aircraft 1. No person parachuting from an aircraft in distress shall be made the object of attack during his descent. 2. Upon reaching the ground in territory controlled by an adverse Party, a person who has parachuted from an aircraft in distress shall be given an opportunity to surrender before being made the object of attack, unless it is apparent that he is engaging in a hostile act. 3. Airborne troops are not protected by this Article. Not many states have ratified Protocol I but it is an accepted principle of international humanitarian law that targeting persons, other than airborne troops, parachuting from an aircraft in distress is a violation of the customary laws of war and is binding on all belligerents, whether or not they have ratified them.