When aviation decisions are made in the heat of the moment, even minor issues can have fatal consequences. A dashcam captures the horrific crash as a Taiwanese airliner nosedives into a river. Warned of a problem that doesn't exist, a KLM crew inadvertently sparks a cascade of deadly errors. And, for a revolutionary new spacecraft, a split-second decision spells a supersonic disaster.

Following three horrifying crashes, investigators uncover fatal flaws in the procedures intended to stop aircraft from crashing into mountains.