Piper PA 30 N7409Y accident near Plainfield, Illinois

Probable cause

The pilot's failure to maintain airplane control during an en route climb near convective activity, which resulted in an aerodynamic stall, an uncontrolled descent, and a subsequent in-flight breakup due to an exceedance of the airplane's design load limitations.

NTSB analysis

The commercial pilot departed on a cross-country flight in the multi-engine airplane and attempted to use visual flight rules flight following from air traffic control during the flight. The availability of this service is based on controller workload, and, as the flight neared an area of Class B airspace, the controller discontinued flight following services and instructed the pilot to remain clear of the Class B airspace. The airplane then climbed from its cruise altitude of 8,500 ft mean sea level (msl) to 10,300 ft msl while losing airspeed until reaching about 48 kts, well below its lowest published stall speed. The airplane subsequently entered a series of descending turns, reaching an airspeed of about 211 kts that exceeded the airplane's design maneuvering speed. The airplane experienced an in-flight breakup.

Weather radar imagery identified reflectivity values consistent with convective activity immediately adjacent to the airplane's position just before the time of the accident. It is likely that the pilot initiated the climb in order to remain clear of the developing convective activity, and it is also likely that the airplane entered instrument meteorological conditions sometime between the initiation of the climb and the loss of control. The convective conditions present at the time of the accident were conducive to the development of updrafts, downdrafts, and turbulence; however, there were no recorded pilot reports for this area and the exact conditions encountered by the accident airplane could not be determined.

Although maintenance records indicated that the airplane had undergone recent maintenance to the left wing and rivet holes in the left wing spar exhibited signs of anomalous installation, this likely did not contribute to the accident, since a performance study determined that the airplane exceeded its design maneuvering speed, which put the airplane at risk of exceeding its design load limitations and the subsequent structural failure.

Toxicology findings indicated that the pilot was using two antidepressants, one of which, trazodone, is potentially impairing. While symptoms of depression often include cognitive deficits, it is impossible to know what, if any, medication side effects or cognitive symptoms the pilot may have been experiencing at the time of the accident. Therefore, whether his depression or its treatment contributed to the circumstances of the accident could not be determined from the available information.

Text from the NTSB. Open the NTSB docket for CEN16FA276 for the full record.