Extended functional impairment characterized by sick leave and disability after a single disaster has not been documented before. This prospective, longitudinal, case-control study applied growth mixture modeling to predict trajectories of functional impairment in oil rig workers, survivors (n = 68) and a matched comparison group (n = 84), over 27 years after the 1980 North Sea oil rig disaster. In the initial 12 years post-disaster, survivors displayed higher rates of functional impairment than the comparison group. A minor group of survivors (n = 8, 11.8%) demonstrated persistent functional impairment from the start and remained unable to work during the subsequent three decades. Long-term sick leave and disability were related to perceived peritraumatic death threat and a propensity towards social withdrawal. Most survivors (n = 60) revealed no major functional impairment. The study indicates that functional impairment should be counteracted in the early support after a single disaster.