Tom Gorham

Tragedy struck when the Space Shuttle Challenger disintegrated just 73 seconds into flight. Hours earlier, engineers argued to cancel the launch, amid fears of such a tragedy – so why did it go ahead?

Concorde was an icon of the skies, but on 25 July 2000, Air France Flight 4590 left Paris for New York and caught fire during take-off before crashing to the ground just over a minute later, killing everyone on board. The tragedy brought an end to the dream of supersonic passenger flight. But what caused the disaster? Investigators, survivors’ loved ones and those who examined the wreckage recall the tragedy and describe how the evidence led to a shockingly simple conclusion about what went wrong.

Massive engineering mistakes occur all over the world, some with devastating consequences. These are assessed by design teams, eyewitnesses, and experts who analyze what went wrong and how the engineers fixed the mistakes.

Survivors and witnesses recall March 11 2011 - when Japan was hit by a devastating tsunami of 40-foot waves, killing 20,000 and triggering a nuclear meltdown.

The terrorist hijackings and destruction of the Twin Towers were a defining moment in human history. Nearly 3,000 people were killed, triggering the war on terror and changing the way we live today. Rescue workers, survivors and witnesses relive the traumatic events of 9/11, some telling their story for the first time.