In the third Geneva Convention of 1929 it had been agreed that during the war the transport of wounded by the Red Cross was not to be attacked. To ensure that the enemy knew that the planes were used for this purpose, they had to be painted white with a red cross.
The condition however was that the aircraft never took part in battle. That was not the case with the aircraft used by the 806th Flight Nurses of MAES: the evacuation flights were "one-way flights" from the front to the hospital. On the way to the front the aircraft were loaded with equipment: fuel, weapons, ammunition, supplies, and so on. The aircraft were used to drop paratroopers and tow gliders.
The result was therefore that an evacuation flight was a legitimate war target and the occupants - including nurses of 806th MAES - ran the risk of being shot down by enemy aircraft and anti-aircraft guns.
