Investigation Summary
The loss of G-ALYP was a watershed moment in aviation history. As the third Comet ever built, its failure exposed a previously misunderstood phenomenon: the effect of repeated pressurization cycles on high-altitude jet airframes. Investigators from the Royal Aircraft Establishment (RAE) performed a pioneering 'full-scale' fatigue test by placing a sister Comet airframe in a giant water tank to simulate pressure cycles. They discovered that the stress concentrations at the sharp corners of the square windows were significantly higher than anticipated, leading to microscopic cracks that eventually caused the fuselage to rip open like a balloon.
Final Conclusions
The accident was caused by structural failure of the pressure cabin brought about by metal fatigue. The fatigue originated at a stress concentration point at the corner of one of the cabin's square apertures (the ADF windows). This led to explosive decompression and the total destruction of the aircraft in flight.
Video Analysis
The Tragic Story of the de Havilland Comet — An analysis of the design flaws and metal fatigue issues that led to the crashes of the world's first jetliner.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Pressure Cabin
The fuselage was designed to be pressurized for high-altitude flight, but the thin aluminum skin could not withstand the stress cycles at the window corners.
ADF Windows
Two square apertures in the roof for the Automatic Direction Finder antennas where the fatigue cracks originated.
Interesting Facts
- 01G-ALYP was the first jetliner to ever enter commercial service (May 1952).
- 02The investigation involved the first-ever large-scale recovery of wreckage from the deep sea floor using sonar and divers.
- 03The square windows of the Comet 1 were identified as the primary design flaw.
- 04All 35 people on board, including 10 children, perished in the accident.
- 05The crash led to the permanent grounding of the Comet 1 and a total redesign of the aircraft.
Safety Actions & Advisories
Fuselage Redesign
Future jet aircraft, including the Comet 4 and Boeing 707, were designed with rounded windows to eliminate stress concentration points.
Fatigue Testing
Mandatory full-scale fatigue testing of airframes became a standard requirement for the certification of all new pressurized transport aircraft.