Maybe phones should all have an emergency distress mode--a separate mode like airplane mode that conserves power and sends out an intelligently designed sequenc

Maybe phones should all have an emergency distress mode--a separate mode like airplane mode that conserves power and sends out an intelligently designed sequence of pings using a standard protocol, some of which encode GPS data, some try to reach a cell tower, others just try to just broadcast a ping as far as possible to get attention, maybe even an attempt to ping a satellite. Also, make every phone a receiver/decoder of this peer-to-peer protocol (no cell tower required), so that searchers would become a swarm antenna using only the personal phones everyone already had. You would have to have your phone, but lots of hikers and runners do, and you would have to be conscious and able to turn on the distress mode if you got in trouble, but in most cases people are, at least part of the time. There would also have to be a cost to using the system, so people wouldn't constantly do it as a prank. This upgrade to the tech we already have could prove useful in so many ways.