As a pilot with some engineering background I want to suggest a solution to this problem of locating aircraft after a crash. The fms knows where the aircraft is at any point in time in terms of longtitude and latitude. This changes rapidly during flight I know there's a page on the fms in my previous aircraft for getting this information. Upon impact greater than a particular force(g). This will prevent it being activated during severe thunderstorm. The black box will send out the last position reading in lat and long format to a distress box on any aircraft within say 100 miles. This will continue for about twelve hours. Another aircraft along that route can pick up these details and pass it on. Every point on the ocean surface has a postion in lat and long coordinates.
The technology to do this is out there, they simply need to use it. My junior brother has a $300 phone that figured out without any input after some weeks where he worked and on what days as this was regular to a tee. He started getting a text everyday at five minutes before 9am that it was time to start driving to work. On Thursdays and Fridays that he was always off he never gets a text.
These aircrafts costs tens of millions of dollars and they a really telling us they cant find them after a crash. Iphones and Samsung phone tell you which city or street your friend is calling from! Any input or suggestion will be appreciated.