"All right, good night."
Those are the last words heard from the cockpit of Malaysia Airlines Flight 370, said Zulazri Mohd Ahnuar, Malaysian civil aviation officer.
Who said them? Was it the captain or his first mate? Or someone else in the cockpit with them?
Since MH 370 went missing Saturday, there have been more questions than answers, including about the pilots.
Malaysian investigators are considering the possibility that one of them was involved in its disappearance, the transportation minister said Friday.
Information from U.S. officials indicated that the Boeing 777-200ER passenger jet may have flown for five hours after last contact with the pilots.
The duty of all pilots is to aviate, navigate and communicate, in that order, an aviation expert has told CNN.
Someone may have kept aviating, but either they couldn't - or wouldn't - communicate.
This is what we know about the 50-year-old pilot captain and his 27-year-old first mate.
See the full story on CNN.com.