When we go on EMS calls we likely need to fly folks off the island (there's no hospital here). When we do we work closely with our air assets, choppers, small planes, etc. and the incredibly skilled pilots and flight nurses inside them. Apparently, when they depart, each air asset needs to account for people on the plane (in the case they crash) and they do this by counting the number of souls aboard. They don't differentiate between crew and patient/s as each alive person is a soul aboard, dogs are not counted as a soul aboard, neither are cadavers or unborn children (which makes me think it's not a religious remnant).