Wheelsright
I do not think that there is any example of a commercial aircraft being located other than by witness, ATC and/or conventional search.
This was my understanding too.
Perhaps someone knows if Sully's landing in the Hudson caused the aircraft ELT to work. I have not heard of any water landing/crash where the ELT worked.
I have only heard of military PLB's (SARBE) actually locating people. I was involved in the SAR for a P3 North of Malin head that nobody realized had crashed till we got a report from a small GA aircraft of hearing a PLB on 121.5.
I have only heard of one successful ELT alert that was the crash of a politician in the North US where apparently the ELT worked.