Related Rule
Israel
Practice Relating to Rule 48. Attacks against Persons Parachuting from an Aircraft in Distress
With reference to Israel’s Law of War Booklet (1986), the Report on the Practice of Israel states: “IDF [Israel Defense Forces] internal regulations and practice prohibit firing upon enemy airmen parachuting from their aircraft in distress (as opposed to offensive para-drop operations).” 
Report on the Practice of Israel, 1997, Chapter 2.1, referring to Conduct in the Battlefield in Accordance with the Law of War, Israel Defense Forces, 1986, p. 10.
Israel’s Manual on the Laws of War (1998) states: “It is allowed to fire upon paratrooper forces even when they are still in mid-air.” 
Israel, Laws of War in the Battlefield, Manual, Military Advocate General Headquarters, Military School, 1998, p. 43.
Israel’s Manual on the Rules of Warfare (2006) states:
Parachutists in mid-air may be shot! Paratroopers jumping in operational activity are combatants in the full sense of the word, and may indeed be shot. The myth originates from the (genuine) prohibition applicable to targeting an air crew that is baling out. That is because air crew, as distinct from a paratrooper, becomes hors de combat by abandoning its plane. By contrast, the paratrooper’s military advantage lies specifically in the act of jumping, and granting immunity to that act makes no sense. 
Israel, Rules of Warfare on the Battlefield, Military Advocate-General’s Corps Command, IDF School of Military Law, Second Edition, 2006, p. 50.
[emphasis in original]
The Manual on the Rules of Warfare (2006) is a second edition of the Manual on the Laws of War (1998).