Brazilian news media say passengers trapped in a plane without air conditioning in the brutal heat of the southern hemisphere summer opened the emergency exit doors.
Globo television network broadcast videos shot inside the plane that show overheated passengers fanning themselves before deciding to open the emergency exits.
The 130 passengers on yesterday's flight from Rio de Janeiro to Sao Paulo were trapped inside the jet on a runway for an hour.
The Brazilian airline Gol said in a statement today the air conditioning units used on the ground were defective. The airline eventually moved the passengers onto another jet. It says "no measures were spared to minimize the discomfort to passengers."
Rio is experiencing a heatwave, with temperatures hitting 104 degrees Fahrenheit (40 degrees Celsius).
