11.   Another program, known as Flight Operational Quality Assurance, uses information taken from flight data recorders on routine flights to track potential problems.

12.   As is the case with most corporate jets, it did not carry a flight data recorder.

13.   As a practical matter, the U.S. Navy has extensive experience in retrieving wreckage and the flight data recorder and cockpit voice recorder of such planes.

14.   As is the case with most corporate jets, this one did not carry a flight data recorder.

15.   Because flight data recorders are principally intended for post-crash analyses, the boxes are positioned in the most crash-resistant part of the airplane, the tail.

16.   Both boxes from the plane that crashed in Pennsylvania and the flight data recorder from the Pentagon plane have been analyzed, but are also closely held.

17.   Both the cockpit voice recorder and the flight data recorder in Pennsylvania have been sent to their manufacturer because their circuit boards are crushed, Tucker said.

18.   -- Commercial aircraft must have cockpit voice recorders and flight data recorders.

19.   A flight data recorder, recovered earlier also showed power interruptions but it was not clear whether these occurred at the same time.

20.   A flight voice recorder, officials say, appears to capture Batouty in the cockpit and muttering a short prayer before the plane dove.