"Roger That" / "All right, Good night"
Maybe a journalist at the next press conference could clarify these rather informal (and in the second case, nonstandard) radio transmissions:
- did they both happen, they have both been variously reported ?
- were they judged to have been said by the same pilot, ie the co-pilot ? (it's fairly normal practice for one pilot to fly the aircraft and the other to handle the radio, though it's not uncommon for both pilots to talk at times on the radio)
- however, at an international boundary it would be quite unusual, though not a sackable offence, for the pilots to get away with such a casual hand-off from Malaysian ATC without at least their callsign
- so perhaps they were just responding to something very trivial, or trying to send a coded message (under duress?) back to the airline / ATC, or a third party unfamiliar with correct radio terminology was making the calls ?
Given the informality, they should really have been asked by ATC for a "readback" of their instructions to "Contact Vietnam on frequency xxx.x" (or something like that) to be sure that MH370 was transferring to the correct ATC in the chain.
Readbacks are a standard requirement between ATC and pilots for key events such as radio frequency handovers and changes to altitude, heading, etc. It would be useful to know what Malaysian ATC said just before the two quoted pilot transmissions above to see what readbacks (if any) would have been expected. One readback ignored by MH370 may be OK on a quiet night, two becomes more suspicious.