@amos regarding ELT
The reason I am asking this forum about the ELT is that Google gives a huge amount of nonspecific information on ELT. This forum has experts who can tailor the information specifically to the B 777.
Let me add another question. What type of crash / situation will make a ELT signal not be detected ? I.e it is designed to with stand ground impact ? and designed to float , so shouldn't it "always" work in a crash ?