HUMAN ELEMENT G(t)

Treating human as a element of control loop has quite a long story; important anywhere there, where human actions have direct and quick influence on safety of others.

In particular aviation, marine, wheeled transportation are of interest; time-factor is the issue.

Under normal conditions human brain still effectively competes with auto-pilots, both electromechanical/ hard wired/analogue-steered as well as electronic/digital/software-based.

However, particularly disturbing are some spectacular cases where two pilots simultaneously omitt the same (&significant) point from checklist, or stubbornly, minutes-long give contradicting commands to control stick. Or experienced marine officer, through quite long sequence of commands insist on breaking written&learned maps, instructions and procedures. Or bus driver suddenly falls asleep with busload of passengers behind.

Measuring response to standard signals (as Dirac's delta, unitary, sinusoid, etc) make possible to assess human brain as control element with non-linear transmittance function. Or even model him with computer program.

Multiplying human units at control position normally increases safety; it is even easier with computer-based auto-pilots, where presently used redundancy is already 3 out of 5 or 4 out of 5 - no technical problems to increase it further.

But the engineering point is always like that: is the failure internally-induced ( by design, material or workmanship) or externally (by intentional or non-intentional influence).

The first is easier to reduce , just by good care. The second would be easy, if we could provide ideal isolation.