Asynchronous evolution

Leplat has noted that many accidents relate to asynchronous evolution [112], where one part of a system (in this case the hierarchical safety control structure) changes without the related necessary changes in other parts. Changes to subsystems may be carefully designed, but consideration of their effects on other parts of the system, including the safety control aspects, may be neglected or inadequate. Asynchronous evolution may also occur when one part of a properly designed system deteriorates. 

Because those who had designed the control structure recognized the potential for some distance to develop between the training of the AWACS crew members and the continually evolving practice in the no-fly zone (another example of asynchronous evolution of the safety control structure), they had instituted a control by creating staff or instructor personnel permanently stationed in lUrkey. Their job was to help provide continuity for U.S. AWACS crews who rotated through OPC on temporary duty status, usually for thirty-day rotations. This shadow crew flew with each new AWACS crew on their first mission in the TAOR to alert them as to how things were really done in OPC. Their job was to answer any questions the new crew... 

This level of the control structure contains more examples of inconsistent mental models and asynchronous evolution. In addition, this control level provides interesting examples of the adaptation over time of specified procedures to accepted practice and of coordination problems. There were multiple controllers with confused and overlapping responsibilities for enforcing different aspects of the safety requirements and constraints (figure 5.8). The overlaps and boundary areas in the controlled processes led to serious coordination problems among those responsible for controlling aircraft in the TAOR. 

The one simulator session they did receive was less than effective, partly because the computer tape provided by Boeing to drive the exercise was not current (another instance of asynchronous evolution). For example, the maps were out of date, and the rules of engagement used were different and much more restrictive than those currently in force in OPC. No Mode I codes were listed. The list of friendly participants in OPC did not include UH-60s (Black Hawks) and so on. The second simulation session was canceled because of a wing exercise. 

Inadequate simulator and spin-up training was provided to the AWACS crews. Asynchronous evolution occurred between the changes in the training materials and the actual situation in the no-fly zone. In addition, there were no... 

In the work by Shida et al. [45] a synchronous concerted double proton transfer is found to be the major mode of the reaction, which is confirmed in a recent molecular dynamics calculation by Wolf et al. [46]. In his molecular dynamics calculation the time evolution of the potential energy was additionally taken into account. The double proton transfer has also been investigated in a Car-Parinello ah initio molecular mechanics study by Miura et al. [41]. Quantum fluctuations are shown to cause significant deviations from the minimum energy path. While an asynchronous movement of the two protons close to the equilibrium structure was... 

Kuukasjarvi T, Karhu R, Tanner M, Kahkonen M, Schaffer A, Nupponen N, Pennanen S, Kallioniemi A, Kallioniemi OP, Isola J (1997) Genetic heterogeneity and clonal evolution underlying development of asynchronous metastasis in human breast cancer. Cancer Res 57 1597-1604... 

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