Roll calls would be nice, but in evacuation and rescue situations that is not always possible. I worked on the receiving end for nursing home patients received during Hurricane Katrina. The pilots were bringing in plane after plane of people to us. They said they literally just opened the doors and let anyone and everyone on who was standing there until it was full. The hope is that on the other end someone is accounting for each person, but in the cases of nursing home patients they don't always come with medical charts and sometimes cannot even tell their own name.