When Katrina struck I remember the images of survivors waving from their rooftops tops during the day and I got to thinking what do they do at night? Then it struck me, use the night to work reverse cycle. Basically let's improve how the 12 of the 24 hours that are dark, are utilized. With new technologies like drones & smart phones we can do much better than SOS which was first recognized in 1905. SOS only tells you someone is there in need of help.
Basically the post disaster visual 911 system works like this and does not depend on connectivity:
a. Over 90% of Americans carry their cellphone or smart device with them all the time. In a sense the majority of the population is equipped with a night time visual signaling device. (see attached)
b. A disaster strikes.
c. People trapped in the disaster stricken area utilize the night to visually signal first responders using their cellphones, smart devices or other lights. Children = red, women = green, men = blue, pets/livestock = yellow. In the future it would be good to include dual color codes to ID people with disabilities. If the visual signal is constant the user is OK, if the visual signal is flashing the user is in need of assistance. See attached image of what I imagine a future disaster stricken city could look like to a responder.
d. Responder now utilize UAS's, helicopters, planes, or high ground to look for the visual signals and make note of the information (location, condition, group make up). This way they can better preplan first light rescue operations or start night time rescue operations. Here is a link to a Coast Guard pilots statement regarding how lights ID'd humans and that started days of rescue operations after Katrina-
e. For those caught without a cellphone app or other device capable of emitting a colored signal they could signal using white light from the phones LED flashlight or other lighting source. The responder would still know someone is there but would not know if they were a man, woman, or child. Here is a link to an article which discusses why children are different from adults during MCI's - http://www.jems.com/print/33130
Basically would having the additional visual information (survivors location, condition & group makeup) provide by survivors found in the disaster stricken area and gathered at night by responder improve outcomes associated with SAR? It costs survivors nothing to signal and it cost responders nothing to look for those signals.