I am having some serious trouble believing that it is beyond the ability of the worlds aircraft manufacturer's to retrofit several EPIRB's to the outside of the fuselage of modern airliners.
Google; SMARTFIND G5 GPS (AUTO FLOAT FREE) they cost about £500
MH370 would have been located in minutes and the wreckage found in hours.
With the relatively simple addition of a solid state memory unit storing the last six hours of information fed to the FDR/CVR would result in EVERYTHING that had happened being known within hours not days or weeks or years or never....
For God's sake, I could build one
