NTSB Identification: CHI00FA006.
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Accident occurred Saturday, October 09, 1999 in HOLLAND, MI
Probable Cause Approval Date: 01/18/2001
Aircraft: Dassault DA-900B, registration: N523AC
Injuries: 1 Serious,4 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The flight experienced a series of pitch oscillations while on descent to an assigned altitude of 11,000 feet mean sea level(msl). The flight attendant was seriously injured. The Captain reported that when he was at about 11,400 feet msl, it appeared the airplane was going to descend below the assigned altitude. The First Officer, who was the flying pilot in the left seat, reported that he pulled back on the airplane's yoke to initiate the level off without disengaging the autopilot. He reported that when he relaxed the back pressure on the yoke, the airplane pitched nose down violently and a series of three to four pitch oscillations occurred before the airplane was brought under control. The aircraft load factors reached magnitudes between +3.3g and -1.2 g. The flight attendant was not wearing a seat belt at the time of the incident. The inspection of the airplane revealed no pre-existing anomalies. Neither the autopilot's pilot manual nor the airplane's flight manual contained a Warning, Caution, or Note that explicitly stated not to manually override the autopilot. On October 18, 1999, Falcon Aviation issued Newsflash 52 that notified operators not to manually apply control yoke forces in an attempt to control the aircraft when the autopilot is engaged.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The copilot's improper use of the autopilot system while leveling the flight from descent, resulting in an inadvertent pilot-induced pitch oscillation of the airplane. A factor was the flight attendant not wearing a seat belt at the time of the occurrence. Full narrative available
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