Originally Posted by
NazgulAir
jcjant, Christiaan --
The ELT(s) would be of the mounted type, and sink along with the ship no matter how much buoyancy capability the small ELT box has. And many of these have NO buoyancy at all.
To add some further info, from the BEA report S1.12.2:
An ELT distress beacon with manual tripping was also recovered. This had not been actuated. Its switch was found in the “OFF” position.
So that is what happened to at least one of them, I am not sure how many (or which type) would have been on board, but I am pretty sure that there is no requirement to carry automatic activation ELTs. I think the primary rationale for ELTs is tracing of floating survivors (who will activate them), not automatic location of wreckage.