The truth:
1. "In-flight metal fatigue failure leading to explosive decompression and breakup."
2. "Captain Smith had 4,608 flying hours on the Boeing 707, but only one hour on the new type 334C, which furthermore had been under instruction.[5] The official investigation concluded that the aircraft and its four engines were in working order—primary fault lay with the captain and first officer, in that they "failed to maintain a safe airspeed and altitude and a positive climb by not observing flight instruments during take-off"; no blame was attributed to the third pilot, whose responsibility it was to monitor the radio, and who was unable to monitor the flight instruments from his position in the cockpit.[2] Secondary factors that may have contributed to the accident included:
Loss of situational awareness
The crew had no visual reference in the dark, leading to spatial disorientation.
The crew used a flap retraction sequence from the 707-B series which removed flaps in larger increments than desirable for that stage of the flight, leading to a loss of lift at 600 feet (180 m) above ground level.
Temporary confusion on the part of the pilots when reading the vertical speed indicator, which was different from the A and B series of the aircraft to which they were accustomed.
The drum-type altimeter fitted to the aircraft, was notoriously difficult for pilots to read;[6][7] the pilots may have misread their altitude by 1000 feet.
Flight deck distraction as the result of a bird strike or other minor occurrence.
After investigating this accident as well as a number of others that also involved controlled flight into terrain, the Federal Aviation Administration determined that a ground proximity warning system would have helped to avert some of the accidents. New regulations were therefore introduced from February 1972 requiring all turbojet aircraft to be fitted with the system.[8]"
3. "In-flight fire (cause undetermined and disputed)"
4. "Loss of control, Pilot incapacitation" "[speculation:]the pilot of the plane suffered a heart attack while on approach and the co-pilot was unable to regain control of the aircraft"