Já tinha visto isto há uns meses no canal do VASAviation ( ).
Citando uma das respostas:
"VASAviation - Hi, the balloons described in this recording are unmanned hot air balloons that unfortunately became a tradition in my country, long time ago. Their occurrence greatly increase during the months of June, July and August during St. John's festivities. It is considered a crime against aviation safety, but local authorities are slow to enforce that. The CENIPA, the Brazilian center for investigation and prevention of accidents made several comprehensive studies about this problem, made many suggestions but so far no decisive move has been made. Few years ago, in São Paulo, the police apprehended one of the largest ever built: the monster was 190ft tall! Thankfully this one didn't make into the air but the tradition lives on. We are all afraid that some major problem is a matter of time."