What happened
On May 12, 1999, a Cessna 172 G, registration PT-COD, departed from an unauthorized airstrip in the Muigaraku tribe area, bound for São Félix do Xingu, Pará. The aircraft was carrying the pilot and three passengers as part of a non-profit mission. Approximately ten minutes into the flight, the pilot received HF radio reports of a large cumulonimbus (CB) cloud formation near the destination, indicating that visual flight conditions would be impossible upon arrival.
Rather than returning to the departure point, the pilot continued the flight, descending from 6,000 feet to 2,000 feet. As the aircraft approached the Canápolis mining farm, the pilot attempted to land at a nearby location to avoid the storm. Witnesses on the ground reported that a powerful windstorm hit the area, which had already caused damage to local buildings. During the approach, the aircraft was caught by severe turbulence and wind components, causing it to be drawn into the edge of the CB formation. Witnesses observed the aircraft's right wing separate in flight, after which the aircraft plummeted vertically into the dense jungle.
The investigation
CENIPA investigators located the wreckage five days after the accident in a remote area of the Amazon rainforest. The investigation established that the aircraft struck the ground in a vertical, uncontrolled attitude. While the right wing was not recovered, analysis of the vertical and horizontal stabilizers indicated that the airframe had been subjected to extreme positive G-loads.
The investigation also uncovered significant maintenance irregularities. The aircraft was equipped with a Lycoming engine and a Sensenich propeller that were outside the manufacturer's type certificate specifications. Furthermore, maintenance records were incomplete, with a significant gap in documentation between 1983 and 1993, and evidence that required periodic inspections had been neglected. All four occupants perished in the crash, and the aircraft was a total loss.
Findings
- Deficient Flight Planning: The pilot failed to plan a safe alternative or return to the origin after receiving weather alerts.
- Adverse Meteorological Conditions: Severe wind components and turbulence associated with the cumulonimbus formation contributed to the loss of control.
- Improper Judgment: The pilot continued the flight toward a known hazard, attempting to land in an area already experiencing severe weather.
- Flight Indiscipline: The pilot intentionally violated visual flight rules (VFR) by proceeding toward an area where visual conditions were no longer adequate for safe operations.
- Structural Failure: The aircraft likely experienced a structural failure of the right wing due to excessive G-loads encountered during the encounter with the storm.