The de Havilland Comet was the world's first commercial jet airliner, and in 1954 two of them broke apart in mid-air within months of each other. The investigation that followed is one of the foundational case studies in aerospace engineering — and this Spanish-language video walks through exactly what went wrong and why it still matters.

The villain wasn't a single bad part — it was metal fatigue concentrated at the corners of the Comet's square-ish cabin windows. Each pressurization cycle stretched the fuselage skin, and the sharp corners acted as stress concentrators, multiplying local strain until microscopic cracks propagated and the cabin exploded. The Royal Aircraft Establishment's full-scale water-tank fatigue test — submerging an entire fuselage and cycling pressure thousands of times — became the template for how airframes are validated to this day.

The lessons that fell out of this disaster are still everywhere in modern aviation: rounded window corners, mandatory fatigue testing, redundant load paths, and the entire field of fracture mechanics gaining engineering legitimacy. If you fly in a tube with oval windows, the Comet is the reason.

Note: The video is in Spanish, but for viewers who can follow it (or use auto-translated captions), it's a substantive look at a real engineering failure rather than a clickbait listicle.