A Fokker 50 cargo plane, registered 5Y-CET, was destroyed when it impacted a residential area at Utawala, Embakasi, shortly after takeoff. All four on board were killed. The airplane departed runway 6 and climbed slowly attaining no more than about 50 feet above ground. The flight path continuously deviated left of the extended runway centerline at an airspeed of 100 knots, which was also the lift off airspeed. The airplane subsequently collided with the building, about 2.1 kilometers north-northeast of the runway departure end. The airplane impact attitude with the building was about a 120ø left roll angle. The cockpit voice recorder (CVR) data revealed aural warning alerts began about 8 seconds after the takeoff roll was initiated of which thereafter the flight crew also made reference to indications associated with visual warning alerts. However, despite the alerts the flight crew continued the takeoff. The flight data recorder data showed that no. 1 propeller rpm reduced from 100% to 50% where it stabilized at for the remainder of the flight. The decrease in propeller rpm corresponded with an increase of the no. 1 engine torque to about 110% along with the occurrence of the aural warning alerts. According to radar data, the liftoff occurred near the runway end. The no. 2 engine operated normally throughout the entire flight. The day before the accident, the airplane was repositioned from Nairobi-Wilson Airport to Jomo Kenyatta International Airport. The flight was commanded by the accident captain. During that flight, the CVR data disclosed warning alerts similar to those of the accident flight accompanied by the flight crew discussion on the interpretation and significance of the alerts. The investigation did not reveal any actions undertaken before the accident to address any irregularities that may have been associated with the warning alerts during the repositioning flight. Calculations of the aircraft weight and balance that included the post-accident measured weights of the cargo determined that at takeoff the airplane weight was about 500kg over the maximum certified gross weight. Probable Cause: The probable cause of the accident was the decision by the crew to conduct the flight with a known mechanical problem and their failure to abort or reject the takeoff after receiving twenty seven cautions.