Dallas Campbell delves into the Horizon archives to chart the deadly disasters that have paradoxically helped make air travel today the safest it has ever been.

It's a macabre paradox, but almost every advance in aviation safety has been driven by a crash. After every crash, investigators determine its cause and scientists make every effort to ensure the same mistakes never happen again. Dallas Campbell delves into the Horizon archives to chart the deadly disasters that have helped make air travel today the safest it has ever been.