to Edda. No one was rescued by the standby vessel Silver Pit, which took an hour to reach the scene. Of the 212 people aboard the rig, 123 had been killed, making it the worst disaster in Norwegian offshore history since the Second World War and the deadliest offshore rig disaster of all time up to that point. Most of the workers were from Rogaland. At around 21:30 hrs. a vessel from the Dutch company Smitlloyd came on location. The crew of this vessel heard people shouting for help. Maneuvering with great caution the Smitlloyd vessel encountered a life raft from the rig and after checking this raft it was found empty. It was very difficult to get this life raft on deck so the crew let the raft go. 2 more liferafts were found by the Smitlloyd vessel and they also were found empty. The crew heard still people shouting for help but due to the dense fog nobody was seen. The Smitlloyd vessel stayed on location for several days helping the coordinated rescue operation. Investigation In March 1981, an investigative report concluded that Kielland collapsed due to a fatigue crack in one of its six bracings (bracing D-6), which connected the collapsed D-leg to the rest of the rig. This was traced to a small 6mm fillet weld which joined a non-load-bearing flange plate to this D-6 bracing. This flange plate held a sonar device used during drilling operations. The poor profile of the fillet weld contributed to a reduction in its fatigue strength. Further, the investigation found considerable amounts of lamellar tearing in the flange plate and cold cracks in the underlying groove weld. Cold cracks in the welds, increased stress concentrations due to the weakened flange plate, the poor weld profile, and cyclical stresses (which would be common in the North Sea) seemed to collectively play a role in the rig's collapse. Judging by paint on part of the fractured surface, the crack was probably due to improper work during the rig's construction in 1976. Other major structural elements then failed in sequence, destabilising the entire structure. The design of the rig was flawed owing to the absence of structural redundancy. Kielland was recovered in 1983 at the third attempt. The rig was scuttled later that year in the Nedstrand Fjord after a search for missing bodies had been completed, as well as several tests to