What happened
On February 8, 2020, a Chincul Sacaifi PA-25-235, registration PT-OST, was performing agricultural spraying operations near Itariri, São Paulo. The flight began at the Ana Dias landing strip, where the pilot applied agricultural products to a banana plantation. After completing the initial task, the pilot proceeded to a second area approximately 22 km away to evaluate wind conditions.
During the return flight to the base, the aircraft traversed the Serra dos Itatins, a mountainous region. While flying at an altitude of approximately 500 ft AGL, the aircraft encountered a strong downdraft. Despite the pilot applying maximum power, the aircraft could not maintain altitude and struck dense vegetation. During the emergency procedure to avoid a more violent impact, the pilot's left wing dipped, causing the aircraft to roll and come to rest on its back. The pilot sustained minor injuries, but the aircraft suffered substantial damage.
The investigation
CENIPA's investigation confirmed that the pilot was properly licensed and medically certified, and the aircraft was airworthy and within weight and balance limits. Meteorological data from the Santos Air Base indicated that weather conditions were generally favorable for flight, with no significant storm formations present.
Investigators focused on the phenomenon of orographic turbulence, which occurs when air moves along mountain ranges. The investigation noted that while the flight altitude was within regulatory limits for agricultural operations in uncontrolled airspace, it was significantly lower than the recommended altitude of 4,000 ft, which would have provided a safer margin to avoid the effects of mountain-induced turbulence.
Furthermore, the investigation scrutinized the operator's safety management. It was discovered that the company's Safety Risk Management (SRM) for the specific operation had not been updated since 2015, and no specific risk assessment had been conducted for the flight on the day of the accident.
Findings
- Flight planning: The pilot's decision to fly at a low altitude through a known area of mountain-induced turbulence contributed to the loss of control.
- Management oversight: The operator failed to provide adequate safety supervision, specifically regarding the implementation of updated risk management processes for their agricultural operations.