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(CNN) – The last known transmission from missing Malaysia Airlines Flight 370 was a simple, "All right, good night." Shortly after, the plane's transponder stopped sending signals.
Aviation expert and former commercial pilot Jim Tilmon is "troubled" by that timeline.
"The last known transmission from the cockpit was stated without any emotion, or without any indication that anything was wrong. And moments later, literally moments later, the transponders went off the line," said Tilmon.
"Now, what happened in that little time span between 'Everything's okay, roger, have a nice night,' and transponder is off the line, and no communication whatsoever after that point?" said Tilmon.
Transponders are not automatically on while the plane is in the air.
"Pilots don't like to have anything in the cockpit that you can't turn off. You don't know what you're going to need," said Tilmon, who logged thousands of hours flying as a commercial pilot.
"(But) I can't imagine a good reason for turning it off unless there was an electrical situation that could not be handled in another way," said Tilmon. In his 29 years of flying, the retired pilot said he never willfully cut communication with ground control.
For more of our interview with aviation expert Jim Tilmon, check out the video above.