What happened
On a flight departing from Porto Alegre toward São Borja, a twin engine aircraft, known as 'São Pedro do Rio Grande', encountered difficult flying conditions. The flight was originally filed under IFR procedures at an altitude of 4,500 feet; however, shortly after departure around 11:00 local time, the pilot requested to proceed under VFR rules. During this period, the aircraft entered clouds and experienced significantly reduced visibility.
While navigating through these obscured conditions, the plane struck the slope of Cerro Cortelini, situated in the vicinity of São Francisco de Assis. The impact resulted in 12 fatalities, with no survivors reported among the occupants. The passengers and crew were traveling back to São Borja following a visit to the site of a previous aviation accident involving a Panair Constellation that had occurred two days prior.
Findings
The investigation determined that the primary factor in the accident was controlled flight into terrain.