eye tracking can be used to help understand how to improve anything from the layout and navigation of a new airport terminal all the way through to ensuring an airport security scanner operator is scanning the system screen in the way that they have been trained 

Human Factors
Human factors and ergonomics (HF&E), also known as comfort design, functional design, and user-friendly systems, is the practice of designing products, systems or processes to take proper account of the interaction between them and the people who use them.
 
In essence human factors is concerned with what people are being asked to do (the task and its characteristics), who is doing it (the individual and their competence) and where they are working (the organisation and its attributes), all of which are influenced by the wider societal concern, both local and national.
 
Human factors interventions will not be effective if they consider these aspects in isolation. The scope of what we mean by human factors includes organisational systems and is considerably broader than traditional views of human factors/ergonomics. Human factors can, and should, be included within a good safety management system and so can be examined in a similar way to any other risk control system. 
 
Eye tracking can be used to improve anything from the layout and navigation of a new airport terminal all the way through to ensuring that  an airport secuirty scanner operator is scanning the system screen in the way that they have been trained to avoid missing suspicisous items in a suit case.