Incident
A pilot operating an airplane filed an instrument flight rules flight plan via the Direct User Access Terminal System (DUATS), but no evidence of a weather briefing was found. The flight departed in visual meteorological conditions and subsequently entered instrument meteorological conditions while climbing through 12,800 feet.
Flight Sequence
An air traffic controller advised the pilot of moderate rime icing from 15,000 to 17,000 feet, with light rime ice at 14,000 feet. The controller asked the pilot to report if the icing worsened; the pilot responded that it was no problem. The controller coordinated for a higher altitude. At 16,800 feet, the pilot stated that light icing had been present and a higher altitude would be appreciated. About 15 seconds later, the pilot reported a slight rattle and requested a higher altitude as soon as possible. Approximately 25 seconds afterward, the flight was cleared to flight level 200, and the pilot acknowledged. About one minute later, the airplane reached a peak altitude of 17,800 feet before turning sharply left and entering a descent. While descending through 17,400 feet, the pilot transmitted "and N731CA's declaring…" No further transmissions were received.
Wreckage and Environment
The airplane impacted paved surfaces and a wooded median on an interstate highway, resulting in a postaccident fire. The outboard section of the right wing and several empennage components, including the horizontal stabilizer, elevator, and rudder, were found about 1/4 mile southwest of the fuselage in a residential area. Witnesses observed pieces separating during flight and the airplane in a rapid descent. Examination revealed that the outboard right wing separated in flight at a relatively low altitude and then struck and severed parts of the empennage. No preexisting mechanical anomaly that would have precluded normal operation was found.
Weather information indicated that numerous pilots reported icing conditions in the area before and after the accident. At least three flight crews considered the icing "severe." Although severe icing was not forecast, an AIRMET advisory included moderate icing at altitudes the accident pilot was flying. The pilot operating handbook warned that the airplane was not certificated for flight in severe icing conditions and that the pilot must exit such conditions immediately by changing altitude or routing. While the pilot was coordinating for a higher altitude at the time of the icing encounter, it is likely that he either did not know the severity of the icing or was reluctant to exercise his command authority to exit the icing conditions immediately.