The catastrophic result of some of the world's worst engineering disasters caught on tape, examining their likely causes. This episodes recalls an incident 37,000ft over Iowa, when a DC-10 airplane exploded mid-flight. The quick-thinking pilot crash-landed, saving the lives of 184 passengers. How could the disaster happen and what connection do the answers share with the infamous Concorde crash, a fatal British skyscraper fire, and a North Dakota train derailment?