Well, one action would be kicking pilots who shoot down a medical helicopter out of their rides. This way they would have to start over their flight, and make them more cautious about killing no combatants and to check closer the helicopter they are going to take down. For instance you can use a white skin, coupled with nor pylons neither weapons and, of course not to be able to load explosives. After all, it is a med helo, not a saboteur.
That is a good one!