The design dilemma

Single access

Single-access to functions provides many opportunities to access the same functions in a consistent way. Therefore, it is easy to practice, and is best for skill acquisition. Consequently, it is best for routine operation .

Multi access

operators to access functions in various, ways, as in new situations. Therefore, it is adequate for screens that the operators may not have seen before, such as those (in exceptional situations such as in troubleshooting ) or under stress (in unexpected situations such as in emergency operation).

However, multi-access provides many opportunities for operator faults, which are difficult to detect .