Team error

Team error refers to errors that occur in settings where multiple people are working together. Dependency increases the likelihood of human error due to interactions with other seemingly independent defense mechanisms. Engaging multiple people to perform a task does not ensure that the task will be done correctly. One potential dependency is team error, an error of one or more members that allows other individual members of the same group to make a mistake.
Examples.
Pilot/copilot error.
Air Florida Flight 90 at Washington’s National Airport in January 1982 had not been properly de-iced. Snow accumulated on the leading edges of the wings as the flight crew prepared for takeoff. During the after-start checklist procedure, the co-captain called out “engine anti-ice system". The captain reported, “engine anti-ice system off,” and then failed to turn it on. The system should have been on. Consequently, ice interfered with the engine pressure ratio (EPR) system, the primary indication of engine thrust. The copilot called the captain’s attention to the anomalous engine indications at least five times in the last moments before the plane rotated off the runway, but he did not oppose the captain’s decision to continue takeoff. Given the engine indications, he should have insisted on aborting the takeoff. The plane crashed, killing 74 of the 79 people on board.
Diffusion of responsibility error.
At a US Department of Energy production facility in the late 1980s, the shift manager in the operating contractor organization, along with a small group of shift supervisors, planned and carried out the replacement of a faulty pump. Following the work control system had not been successful. The supervisory group reasoned that continued reliance on that system would not be successful. Schedule pressures and frustration led the men to take matters into their own hands and do the work themselves. The team violated procedures governing the work control system, quality inspections, worker certification and union labor rules governing work assignments and responsibilities. No single salaried supervisor would otherwise have considered doing a union mechanic’s job. In the group situation, the rules were discounted.
Strategies tend to reduce the occurrence of team errors.
The following strategies were proposed by the DOE Human Performance Improvement Handbook.