Air Crash Investigation, also known as "Mayday: Air Disasters". It's a Canadian production that airs in several countries. In the USA some episodes are shown in the block "Air Emergency".
Air Crash Investigation recreates the greatest air disasters of the history, and explains exactly what happened. To recreate the disasters, they use dramatic re-enactments of the cockpit, and basically, everything "inside the plane". It's also use an excellent quality 3D animation that recreates everything that happens "outside" the airplane.
Expert pilots and engineers explain what happened: the mistakes of the crew, the bad maintenance, etc...