Aircraft: Beech C90. Injuries: None. Location: Camden S.C. Aircraft damage: Substantial.
What reportedly happened: The 14,500-hour pilot obtained weather information via the internet before the flight. The information included advisories for convective activity and scattered thunderstorms along the intended northwesterly route of flight.
The pilot reported that the takeoff and the climb to cruise altitude were normal with intermittent periods of light turbulence. About 100 miles northwest of the departure airport, he observed weather ahead on the airplane’s on-board weather radar and requested from the en route air traffic controller a 45° westerly course deviation. A course deviation was granted, but because of a potential conflict with a climbing airplane, the pilot was instructed to turn no more than 30° west of his previously established heading.
The pilot complied with the instructions, then determined that he would need an additional 30° to 45° course deviation to avoid weather ahead. The pilot made at least two additional attempts to contact the controller, but received no response.
Post-accident review of air traffic control recordings indicates that the pilot’s transmissions were likely blocked, as one of them was made while another pilot was transmitting and the other was made while the controller was speaking to yet another pilot.
The pilot made an additional course deviation, and the airplane encountered moderate to severe turbulence lasting about two minutes. The pilot continued to the destination airport, landing without further incident. Subsequent examination of the airplane revealed substantial damage to the wing spar, likely due to the turbulence encounter.
The airplane was equipped with a next generation radar receiver, weather radar, and a lightning strike indicator. The pilot was likely aware of areas of significant weather ahead of him, as well as the less significant weather to the northeast and south well before the encounter, and he was definitely aware of the clear weather through which he had just flown. Nonetheless, the pilot continued to fly toward his destination, and toward the significant weather, which resulted in the airplane’s encounter with the turbulence.
Probable cause: The pilot’s in-flight decision to continue toward his destination, through known significant weather, when safer alternatives were available.
NTSB Identification: ERA11LA330
This May 2011 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.