>> there are many backup systems and communication devices available to the crew. you have to remember, they had two -- at least two operating independent radio or voice communication. they had one operating for acars communication and the transponder for radar signal and communication. and for all of those things to be shut out, to stop working means either a massive electrical failure, which is highly unlikely with an aircraft with that many backup systems or something else that we can't even imagine right now which really points to the fact that it is very important that we find this airplane because these are some clues that don't -- aren't normally uncovered in the normal safety systems research that we do. >> keith, how can investigators use this new information to piece together what happened? if you were in charge of the investigation, taking this data point, that the phone was on, what else would you now be