and then the next transmission would normally have been the pilot, what we call the npf. the non-pilot flying, he would have switched his radio to vietnam's wavelength and calmed out, ho chi minh control, this is -- heading xy -- speed xy and vietnam wool have acknowledged it. so this "all right. good night" it's a pleasantry at the end of a radio communication which frankly if you listen to air traffic control in the united states, sometimes you get a pleasant good night, good-bye, good morning, sometimes you don't. >> now given that, would the expectation be that this pilot would then say, hello, to the next airspace, like you said? ho chi minh and if that takes place who would have than kind of recording or data reflecting that that conversation may have happened? >> well, that's the -- that's a very, very interesting point. because the next -- very often you know about a plane incident or a plane accident certainly with air france 447, many of them, we knew about this, because the next person doesn't hear from them. and vietnam goes back to malaysia and said, hang on.