CNN CNN Newsroom April 6, 2014 19:52:00
Don't work as in air france 447. either they are damaged or that kind of a situation. we found in the 9/11 investigation the black box was destroyed so it was pointless. the biggest draw back on the pingers themselves is damage or not operational. when they selected the frequency for the pinger pulse ps they tried to make them not sound like something in the sea. i think it is a pretty good chance that it is a pinger. it doesn't sound like other things. it is a cyclical emission like a stop watch. so, the limitations are just the mechanical part. if it is putting out sound there
Source: archive.org