common? that kind of casual language? >> well, yeah. it's nonstandard, but that frequency is probably used all the time. and the controllers know that the pilots know and vice versa. >> so technically, we're seeing it on the screen here all right good night technically the copilot should have reread ho chi minh city, 120.9. >> should have read back the frequency to confirm it. but they've probably done this hundreds of times. and it just goes -- >> as far as you're concerned not much to glean from this. >> no. in addition to -- we seem to be focusing on the repeating of the altitude a bunch of times. there's a good time space on the transmissions on those altitudes confirms he's at 350. if i want add higher altitude to go into that air space, the way i coax a controller i want a higher altitude to confirm that i'm still at the same altitude. >> nothing there.