The NTSB cited flight into severe icing conditions in the probable cause of the Oct. 18, 2013 crash of a Cessna 500 Citation I. Both people aboard were killed with the aircraft, N610ED, entered into a vertical dive from 15,000 feet and crashed near Derby, Kan.
The aircraft had departed Wichita-Mid-Continent Airport, Kan. (ICT) at 9:59 a.m. local time on a flight to New Braunfels Regional Airport, Texas. After a previous flight in the accident airplane, the pilot had reported several malfunctioning instruments, including the autopilot, the horizontal situation indicator, and the artificial horizon gyros, the NTSB said. The pilot had the right-side artificial horizon gyro replaced but did not have any other maintenance performed at that time. The pilot was approved under an FAA exemption to operate the airplane as a single pilot, but the exemption required that all equipment be operational. “Despite the malfunctioning instruments, the pilot chose to take off and fly in instrument meteorological conditions,” the Safety Board said.
During the accident flight, the aircraft entered an area with supercooled large water droplets and severe icing. As the aircraft entered that area, an air traffic controller issued a radio frequency change, a change in assigned altitude, and a slight routing change. “It is likely that these instructions increased the pilot's workload as the airplane began to rapidly accumulate structural icing,” the NTSB said, adding, “Because of the malfunctioning instruments, it is likely that the pilot became disoriented while attempting to maneuver and maintain control of the airplane as the ice accumulated, which led to a loss of control.”
The NTSB cited as the probable cause: “The airplane's encounter with severe icing conditions, which resulted in structural icing, and the pilot's increased workload and subsequent disorientation while maneuvering in instrument flight rules (IFR) conditions with malfunctioning flight instruments, which led to the subsequent loss of airplane control.”
The Board added as a contributor the decision to take off in IFR conditions without a functioning autopilot and with malfunctioning flight instruments.