The quote is from Protocol I, dated 8 Jun 1977, to the Geneva Convention of 1949, neither of which had even been drafted in WWII. The 1977 Protocol 1 to the Geneva Convention of 1949 can be seen online at:Geneva convention:
Part III. Methods and Means of Warfare Combatant and Prisoners-Of-War
Section I. Methods and Means of Warfare
Art. 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.
http://www.genevaconventions.org/
http://www.globalissuesgroup.com/geneva/protocol1.html