Event
During a flight from Porto Alegre to Rio de Janeiro, while cruising at an altitude of 33,000 feet, the aircraft entered an uncontrolled descent. No distress call was sent by the crew. The descent rate reached 20,000 feet per minute. At an altitude of 1,500 feet, the aircraft disintegrated in the air and subsequently crashed. Both pilots were killed.
Investigation
The official investigation determined that the crew failed to prepare the flight according to published procedures. They did not follow the pre-departure checklist and did not verify the position of the pressurization mode selector prior to takeoff. At 33,000 feet, both pilots suffered hypoxia, leading to loss of consciousness and situational awareness. The report noted that possibly one of the pilots fell and inadvertently moved the control column, causing the aircraft to enter the uncontrolled descent.