**3.1 Crash of a Boeing 707-321C airplane**

A Boeing 707-321C airplane crashed on May 14th, 1977, in Zambia, Africa, [12]. The accident occurred in daylight and in good weather, and on approach to landing, killing all the six people onboard. The complete right-hand horizontal stabilizer and elevator assembly of the aircraft had separated from the aircraft during flight and was found 200 meters behind the aircraft wreckage. Subsequent investigation of the fractured horizontal stabilizer revealed that the accident was caused by a loss of pitch control following the in-flight separation of the right-hand horizontal stabilizer and elevator as a result of a combination of metal fatigue and inadequate failsafe design in the rear spar structure. Shortcomings in design assessment, certification, and inspection procedures were contributory factors.
