malaysia flight 370 vanishes into thin air. there's been silence from the cockpit. and by 1:37 a.m., a second flight communications system, acars, isn't working either. >> acars was either switched off, or it failed. we don't know which because whatever did happen, this is the crucial moment. we pretty much know that all the comms are disabled, switched off, broken, blown up. >> as an investigator looking at this, what would the determination be, at least at this point, as to what is happening? >> at this point, i've got two different paths. one is that that aircraft was taken over and that the systems were intentionally shut down. the other side would be that there was a singular failure at a common location, and that singular mechanical failure would have done exactly the same thing. at this point in the