Distraction
Distraction (hereinafter, the Factor) is the human factor that is characterized by drawing one's attention away, including mental emotional confusion or disturbance. The Factor is one of the Dirty Dozen of Human Factors.
In aviation maintenance
According to the FAA AMT Handbook,
A distraction while performing maintenance on an aircraft may disrupt the procedure. When work resumes, it is possible that the technician skips over a detail that needs attention. It is estimated that 15 percent of maintenance related errors are caused by distractions.
A distraction could be anything that takes your mind off the task that is being done. Any distraction while working can cause us to think we are further ahead in the process than we actually are.
Distractions can be mental or physical in nature. They can occur when the work is located on the aircraft or in the hangar. They can also occur in the psyche of the technician independent of the work environment. Something as simple as a cell phone call or a new aircraft being pushed into the hangar can disrupt the technician’s concentration on a job. Less visible is a difficult family or financial matter or other personal issues that may occupy the technicians thought process as work is performed. This can make performance of the required maintenance less effective.
Regardless of their nature, numerous distractions may occur during the course of maintaining an aircraft. The technician must recognize when attention to the job at hand is being diverted and assure that work continues correctly. A good practice is to go back three steps in the work procedure when one is distracted and resume the job from that point. Use of a detailed step-by-step written procedure and signing off each step only after it is completed also helps. Incomplete work can be marked or tagged, especially when the technician is pulled from the work by a distraction, and it is unknown when work will be resumed and by whom. Disconnect any connector and leave it plainly visible if an installation is not complete. There is a tendency to think a job is finished when a component is “hooked up.” Similarly, when a step in the maintenance procedure is complete, be sure to immediately lock wire or torque the fasteners if required. This can be used as an indication that all is well up to that point in the procedure.
Mitigating the risk: (a) Once returning to the job, go back through all of the steps to ensure where you left off, (b) Never leave tools or parts lying around. Secure them before leaving the area, (c) Use a detailed checklist.