Should civil aircraft carry systems that would detect an incoming surface to air missile???

Of all the tragedies in a war, the most unfortunate is the loss of innocent lives. We see the human drama played out nightly in the conflicts between Russian separatists in the Ukraine, and elements of Hamas and the Israeli Defense Forces in the Gaza Strip, not to mention plenty of other places throughout the world. A certain degree of innocent suffering is expected for those who live in the area of the conflict, but rarely does it reach into the skies to affect those who have nothing to do with the war below.