This documentary investigates many air crashes and near-crashes in modern history after the introduction of the black box flight recorders. It reveals events that led up to each disaster, the causes of the incidents and the measures recommended in the report by the NTSB or the investigating Commission to prevent a similar incident happening again. It features re-enactments, interviews, testimony, computer-generated imagery, and in some episodes, cockpit voice recordings to reconstruct the sequence of events to the audiences. As of December 2009[update], seven seasons of programs have been produced. For season 4, the series received an updated title sequence and appearance