Lack of awareness

Lack of awareness (alternatively known as lack of situational awareness; hereinafter, the Factor) is the human factor that is characterized by a failure to be alert or vigilant in observing. Situational awareness is the opposite of the Factor, which is considered being one of the Dirty Dozen of Human Factors.

In aviation maintenance

According to the FAA AMT Handbook,

Lack of awareness is defined as a failure to recognize all the consequences of an action or lack of foresight. In aviation maintenance, it is not unusual to perform the same maintenance tasks repeatedly. After completing the same task multiple times, it is easy for technicians to become less vigilant and develop a lack of awareness for what they are doing and what is around them. Each time a task is completed it must be treated as if it were the first time.

Mitigating the risk: (a) Check to see if what you are working on conflicts with an existing modification or repair, (b) Even if you are highly proficient in a task, always have someone check your work, (c) Always ask co-workers to check your work. After completing the same tasks multiple times, maintainers can develop a lack of awareness for what is around them. Common sense and vigilance tend to not be present because they have completed the same task so many times.