What happened
On December 26, 1996, a Beechcraft A-36 Bonanza, registration PT-IZA, departed from Bauru, São Paulo, on an IFR flight to Governador Valadares, Minas Gerais. The aircraft was carrying a pilot and two passengers. During the flight, the aircraft encountered adverse meteorological conditions, including moderate to heavy turbulence while operating under instrument flight rules (IMC).
During this period of turbulence, a passenger moved from their seat to the forward section of the cabin. The pilot reported that the passenger, visibly distressed, began interfering with the flight controls by pushing the control yoke forward. This interference, combined with the pilot's focus on the passenger, led to a loss of altitude and a potential error in control inputs. As the aircraft encountered terrain, it likely struck an obstacle, causing significant structural damage. The impact resulted in the separation of the engine and instrument panel from the airframe. Following the loss of the engine's weight, the aircraft entered a tailspin. The centrifugal forces during the spin, coupled with the loss of structural integrity, caused the passenger (who was unbelted) and the right door to be ejected from the aircraft. The aircraft eventually impacted a eucalyptus plantation in Nova Resende, MG.
The investigation
CENIPA's investigation focused on the sequence of events leading to the structural breakup and the human factors involved. Investigators examined the wreckage distribution, which spanned 1,000 meters, and noted that the engine and instrument panel were found 150 meters ahead of the main fuselage wreckage. The investigation also reviewed the pilot's flight experience, the aircraft's maintenance history, and the operational legality of the flight, noting that the aircraft was being operated by a law firm rather than a certified air taxi operator.
Findings
- The aircraft suffered one fatality and one serious injury among the passengers, while the pilot sustained minor injuries.
- The passenger's movement and interference with the controls likely caused a loss of altitude and contributed to the pilot's loss of situational awareness.
- The investigation determined that the pilot's attention was likely diverted by the passenger's behavior, leading to inadequate control inputs during turbulence.
- The structural failure was triggered by a collision with an obstacle or terrain, which caused the engine and forward components to detach.
- The passenger's ejection was caused by the centrifugal forces of the resulting tailspin and the loss of the cabin door.