Jbr76:
If the aircraft crashed into sea, why hasn't there been an activation of the ELT?
- The ELT antenna was broken off in an impact
- The aircraft went in inverted
- The ELT was not working
- The touchdown was not violent enough to activate it
- The ELT was destroyed by impact forces
- The ELT is like all other ELTs and does not work underwater
This list could be only 1% of the many reasons you could use to explain why there was no signal detected.