Originally Posted by
luckypierre
No, they are activated by unusual G forces on the device. Their absence in this tragedy certainly adds to the mystery.
I believe they are also activated by water.
Originally Posted by
pspercy
.. make an AUV much more effective for "mapping" than a vessel on the surface. .....
Not to forget the thermal layers in such a water column and their effects on signals !
If you want to go there, you have to also take into consideration salinity and depth. All three, conductivity (salinity), depth and temperature (aka, CDT) all effect the speed of sound, which messes with sonar.