4. What happened to the eight black boxes from the four flights? Were they ever found?
The Flight 93 flight data recorders were recovered. The Flight 77 black boxes were also removed from the Pentagon, but one of them (the cockpit 驾驶员座舱 voice recorder) was reportedly too badly damaged to be used. The only boxes not to be recovered were from the World Trade Center impacts.
Photo: New York Gov. George Pataki, left, Police Commissioner Bernard Kerik, center rear, and Barry Mawn, head of the the New York office of the FBI, rear right, stand behind New York Mayor Rudy Giuliani as Giuliani holds up a photo of an airliner flight recorder, known as a "black box," as he appeals to the public in New York, Wednesday, Sept. 12, 2001, for help in locating the devices carried on the planes that crashed into the World Trade Center. (AP Photo/David Karp)