the noninstrument-rated pilot's intentional operation of the airplane with known deficiencies in equipment (inoperative attitude indicator and directional gyro) with an estimated time of arrival after official twilight. Also, poor in-flight planning decision by the pilot for continuing the flight after encountering dark night conditions resulting in spatial disorientation and a loss of control. Contributing to the accident were: the insufficient standards/requirements of the operator for allowing the airplane to be flown by a noninstrument-rated pilot with inoperative attitude instruments with an estimated time of arrival after official twilight, the dark night and an inoperative attitude indicator.