A controlled flight into terrain (CFIT, usually pronounced cee-fit) is an accident in which an airworthy aircraft, under pilot control, is unintentionally flown into the ground, a mountain, a body of water or an obstacle. In a typical CFIT scenario, the crew is unaware of the impending disaster until too late. The term was coined by engineers at Boeing in the late 1970s. Accidents where the aircraft is out of control at the time of impact, because of mechanical failure or pilot error, are not considered CFIT (they are known as uncontrolled flight into terrain), nor are accidents resulting from the deliberate action of the person at the controls, such as acts of terrorism or suicide by pilot. According to Boeing, CFIT is a leading cause of airplane accidents involving the loss of life, causing over 9,000 deaths since the beginning of the commercial jet age. CFIT was identified as a cause of 25% of USAF Class A mishaps between 1993 and 2002.