For one, the sheer size of the plane means that the crew cannot know all that is happening. They are physically isolated from the passengers and any difficulties that may be occurring within the passenger section of the plane. They are isolated from most of the physical structures of the aircraft. Even more important than physical isolation is the mental isolation caused by the nature of the controls. The automation tends to isolate the crew from the operations of the aircraft because the automatic equipment monitors and controls the aircraft, providing little or no trace of its operations to the crew, isolating them from the moment-to-moment activities of the aircraft and of the controls. On the one hand, this combination of relative physical and mental isolation from the details of flying helps contribute to the safety by reducing workload and reliance on possible human variability or failure. On the other hand when the automatic equipment fails, the crew's relative isolation can dramatically increase the difficulties and the magnitude of the problem faced in diagnosing the situation and determining the appropriate course of action.
So why not install CCTV’s and put monitors in the cockpit so that pilots can actually see what is happening to their pitots, engines and control surfaces during flight?
Physical isolation would be alright if the crew were still up to date on the critical states of the device being controlled. The problem is that, increasingly, the physical isolation is accompanied by a form of mental isolation. Zuboff (1989) describes the control room of a modern paper mill: where once the operators roamed the floor, smelling, hearing and feeling the processes, now they are poised above the floor, isolated in a sound-isolated, air-conditioned, glass control room.
So let us see a qualified pilot making periodic rounds of the passenger cabins during each flight, getting a feel for the mood of the passengers, looking out at the wings and engines and generally having a good look, smell and feel of the situation as a whole.
The Kegworth disaster could have been avoided if the problem engine had been correctly identified by CCTV, or even by a competent person simply looking out of the passenger cabin (smoke, flames etc.) before the wrong engine was shut down.
Seems to me that aircraft manufacturers and airline operators today are much too complacent regarding automated flight systems and pilot training programmes.
Aircraft should be designed to be flown (and to land) safely by fully competent and properly trained human pilots, any automated system should be designed to be used as an adjunct to the human pilot's skills, not vice-versa.